Edit: I understand why people are asking for more context. my dexterity is maxed. my charisma is 15 so increasing that increases my modifier by one. I didn't include other information like the campaign or my party because I didn't want to get into the issue of min/max metagaming.
Depends. If your Dexterity isn't 20 yet, I'd recommend taking ASI before any feats. Assuming you have a 20 in Dexterity and a decent Con (>=14), I'd go with Lucky and prioritize it for saving throws, important skill checks, and extremely important RP moments.
Your post isn't giving us a whole lot to go on. Build information, campaign levels and end game goal are important to figure this out.
Do you get up close and shoot and run? Then sharpshooter + crossbow expert.
Do you have fairly high charisma? Inspiring leader is a very underrated feat that I've seen be a literal lifesaver in a party when combat with the big bad comes up.
Do you dual-wield short swords? dual-wielder allows 2 rapiers and +1 AC.
If you're swashbuckler with an odd number dex, then elven accuracy is good, though I don't know how often you'll have advantage.
Charger is another totally underrated feat for Swashbuckler. Action - Dash / Bonus action - Attack +5 damage while still being able to use fancy footwork to get away allows you to run in and lunge at enemies across the battlefield.
Do you need a familiar's help? For this I'd select magic initiate (Booming blade/green flame blade) with find familiar as your daily level 1. Ritual caster allows you to have a familiar with more general magic utility.
Does your DM like to surprise attack you? Not anymore! Slap alert on your swashbuckler to ignore surprise and add +5 to your initiative.
Lucky can be good on any character. Especially if you are crap at rolling dice.
Well im playing a swashbuckler lvl5 right now. I rolled poorly for stats compared to rest of party. started with 17 in dex (even with the +2 from tabaxi) so i took the moderate armour feat at lvl 4 added +1 to my dex and allowed me to use a shield so for that one feat i added +3 to my ac better than just taking the +2 to my dex.
But as you have max dex already look at feats that also add to your stats and give you extra too, if you want to increase a stat.
Depending how you are fighting dual, single, xbow find what you think will help you in your style. For me im planning at 8 to +2dex to max it out 10 magic initiate and 12 i'm not sure yet maybe moible feet for the +10 movement to allow me to really move around the battlefield.
Mostly just choose what you feel will fit in with your character and how you want to play them.
Magic initiate is legitimately one of the better feats available to you, thanks to the ability to grab spells like hex, find familiar, and the blade cantrips from Scag. Find familiar, while not entirely needed thanks to swashbuckler passively giving you sneak attack, can still use the help action to give you advantage to significantly improve your odds to hit. Hex is good to make enemies less likely to succeed in skill checks. Booming blade can help you do disgusting damage against foes if you have a bad/goolock/someone with puppet since you get your sneak attack dice on opportunity attacks when it isn't your turn.
Dual wielder is also pretty good just because of the fact that in straight up combat you get to make x2 the attacks, even if you miss out on cunning action in exchange for it.
If other racial feats are available, Fey Teleportation isn't unreasonable to help you escape being surrounded or being grappled.
Mage Slayer can be quite good if your dm likes to throw casters at your party, since you have great mobility it isn't unreasonable that you can very quickly close into them, and then be able to stay on them and hit them with opportunity sneak attacks.
Sentinel is a more general Mage Slayer, but it lets you punish enemies for trying to hit someone near you with more sneak attack damage.
If you are a wood elf, since you never specified the type of elf you are, Woodland magic for pass without trace is absurdly good on the stealth side, a party wide +10 stealth means that even your heavy armor bros are able to have decent odds of passing most basic stealth checks.
I am onboard with Magic Initiate (wizard) for find familiar alone. It is universally the best utility spell in the game next to wish, haha. Adding two cantrips for either combat (GFB and/or Booming) or just pick up prestidigitation and any other cantrip. You could also just go the more economical route of Ritual Caster and gain a whole slew of helpful abilities for out of combat excellence. Depending on how tight your GM is with spell acquisition, these are your choices starting at level 4 if choosing wizard and an easy link to all the different classes and what they offer.
Which feat should I choose?.
Edit: I understand why people are asking for more context. my dexterity is maxed. my charisma is 15 so increasing that increases my modifier by one. I didn't include other information like the campaign or my party because I didn't want to get into the issue of min/max metagaming.
Depends. If your Dexterity isn't 20 yet, I'd recommend taking ASI before any feats. Assuming you have a 20 in Dexterity and a decent Con (>=14), I'd go with Lucky and prioritize it for saving throws, important skill checks, and extremely important RP moments.
Partway through the quest for absolute truth.
Your post isn't giving us a whole lot to go on. Build information, campaign levels and end game goal are important to figure this out.
Do you get up close and shoot and run? Then sharpshooter + crossbow expert.
Do you have fairly high charisma? Inspiring leader is a very underrated feat that I've seen be a literal lifesaver in a party when combat with the big bad comes up.
Do you dual-wield short swords? dual-wielder allows 2 rapiers and +1 AC.
If you're swashbuckler with an odd number dex, then elven accuracy is good, though I don't know how often you'll have advantage.
Charger is another totally underrated feat for Swashbuckler. Action - Dash / Bonus action - Attack +5 damage while still being able to use fancy footwork to get away allows you to run in and lunge at enemies across the battlefield.
Do you need a familiar's help? For this I'd select magic initiate (Booming blade/green flame blade) with find familiar as your daily level 1. Ritual caster allows you to have a familiar with more general magic utility.
Does your DM like to surprise attack you? Not anymore! Slap alert on your swashbuckler to ignore surprise and add +5 to your initiative.
Lucky can be good on any character. Especially if you are crap at rolling dice.
Or just go with a +2 dex?
this is very helpful, thank you.
Well im playing a swashbuckler lvl5 right now. I rolled poorly for stats compared to rest of party. started with 17 in dex (even with the +2 from tabaxi) so i took the moderate armour feat at lvl 4 added +1 to my dex and allowed me to use a shield so for that one feat i added +3 to my ac better than just taking the +2 to my dex.
But as you have max dex already look at feats that also add to your stats and give you extra too, if you want to increase a stat.
Depending how you are fighting dual, single, xbow find what you think will help you in your style. For me im planning at 8 to +2dex to max it out 10 magic initiate and 12 i'm not sure yet maybe moible feet for the +10 movement to allow me to really move around the battlefield.
Mostly just choose what you feel will fit in with your character and how you want to play them.
Thank you for the advice
Magic initiate is legitimately one of the better feats available to you, thanks to the ability to grab spells like hex, find familiar, and the blade cantrips from Scag. Find familiar, while not entirely needed thanks to swashbuckler passively giving you sneak attack, can still use the help action to give you advantage to significantly improve your odds to hit. Hex is good to make enemies less likely to succeed in skill checks. Booming blade can help you do disgusting damage against foes if you have a bad/goolock/someone with puppet since you get your sneak attack dice on opportunity attacks when it isn't your turn.
Dual wielder is also pretty good just because of the fact that in straight up combat you get to make x2 the attacks, even if you miss out on cunning action in exchange for it.
If other racial feats are available, Fey Teleportation isn't unreasonable to help you escape being surrounded or being grappled.
Mage Slayer can be quite good if your dm likes to throw casters at your party, since you have great mobility it isn't unreasonable that you can very quickly close into them, and then be able to stay on them and hit them with opportunity sneak attacks.
Sentinel is a more general Mage Slayer, but it lets you punish enemies for trying to hit someone near you with more sneak attack damage.
If you are a wood elf, since you never specified the type of elf you are, Woodland magic for pass without trace is absurdly good on the stealth side, a party wide +10 stealth means that even your heavy armor bros are able to have decent odds of passing most basic stealth checks.
This is very valuable advice, thank you.
I am onboard with Magic Initiate (wizard) for find familiar alone. It is universally the best utility spell in the game next to wish, haha. Adding two cantrips for either combat (GFB and/or Booming) or just pick up prestidigitation and any other cantrip. You could also just go the more economical route of Ritual Caster and gain a whole slew of helpful abilities for out of combat excellence. Depending on how tight your GM is with spell acquisition, these are your choices starting at level 4 if choosing wizard and an easy link to all the different classes and what they offer.
Wizard
1st level: Alarm, Comprehend languages, Detect magic, Find familiar, Identify, Illusory script, Magic Mouth, Tenser’s floating disk, Unseen servant.
2nd Level: Gentle repose.
IMHO, Earthdawn is still the best fantasy realm, Shadowrun is the best Sci-Fi realm, and Dark Sun is the best D&D realm.