Hi there! Appreciate everyone's input and effort, thought I'd come to ya'll again for more advice.

I'm in my first DM campaign, and we've gained/lost a few people. We used to have a Paladin who was a "primary tank," whilst I am a Kensei monk ("off tank"). He had twins, so now our group consists of: 1 rogue/warlock, 1 rogue/blood hunter, 1 cleric, 1 bard, and 1 wizard. So... Naturally, I'm the closest thing to a "tank." A kensei monk isn't saying much. As of level 7, I have 18 Dex, 16 con, 16 wis. I rock 17 AC, or 19 with Agile Parry (A contradictive, awesome ability), but it's irrelevant because our DM is having us combat creatures that are much higher difficulty (We're level 7, and we all almost died to one vampire that conveniently clouded the sky to blot out the sun, and KO'd my 60 HP in two hits). Because of this, I feel encouraged to finish Dex, and then max out Con, instead of Wisdom. My experience with Stunning strike has been a less than 20% success rate, which is pretty steep for 6 ki points, and my 17-19 AC helps me avoid the same % of hits; it's my bad for only having a +3 Wis modifier, although the only alternative I know of was a +4.

When I was building this character a few years ago, I decided on 12 monk/4 GS Ranger/4 BM Fighter. As time has gone on, I've sort of built a lot of interest in the Rune Knight (Cloud Rune/Stone Rune in particular, but I know there's a lot of support for the Fire Rune) and now the Echo Knight. I was wondering if any fighter experts, or anyone whose multi-classed Monk/Fighter, have some advice for a situation like this. We're about to hit level 8, so I'll be a level 6 monk, level 2 ranger. Perhaps extraneous information, but I originally intended on being a whipper. However, now I've decided to also grab the sharpshooter feat at ranger 4, and then ASI'ing the rest of the way.

It basically comes down to this.

• Battle Master offers three maneuvers that I think would help the group a lot, especially with no real tank: Brace, Distracting Strike, Maneuvering Attack (The Rogues are all ranged, so Trip Attack would only benefit me; Menacing Attack would also encourage enemies to target my allies). I wanted to get Riposte, but as aforementioned, the DM is throwing things much higher level than us our way, so dodging an attack isn't very likely. I feel this is the route to go because I want to be a team player, and try to help everybody in the group. Plus it's 4d8.
• Rune Knight is very appealing for the passive effects of each rune (Insight/Sleight of hand advantage, and 150ft of darkvision with Gloomstalker), as well as the once per short rest actives. The attack redirection is obviously amazing, even if the attack would hit a familiar. The charm is very interesting because it's a "consistent" 10 rounds of incapacitation, unlike the usual charm effect that can break on damage. I wish I could utilize Giant's Might more, but 1d6 once per turn isn't worth the bonus action; so it'd only be utilized OoC.
• Echo Knight is very, very, very interesting because it adds mobility, another body on the floor, has unlimited uses, can attack for me, extra attacks (at least 3x per long rest).

It's such a weird predicament. Rune Knight fits my characters story the best, Battle Master helps my group the most, and Echo Knight is the one I'm most desiring. So here I am selfishly asking you guys for any advice :(.

Thanks for your time and apologies for my ignorance/offense.

I’d say to do the echo night if you want it the most. Your party only has you as the tank and you have a cleric so I wouldn’t worry about battle master if you don’t really want it. I think that what you want should get dibs over what fits your character a little better if the dm approves.

I'm neither a fighter expert nor have I multiclassed a fighter/monk, and I'm very biased towards the Rune Knight, so keeping that in mind I'll tell you to choose the Rune Knight.

Keep in mind though: The Stone Rune darkvision does not stack with Umbral Sight (If you already have darkvision from your race, its range increases by 30 feet), which is sad but not deal breaking.

Also, I love the fire rune for the tool expertise, but ymmv.

Otherwise I'd go the Echo Knight.

At the end of the day though choose the class that you think will bring you the most fun/satisfaction.

Echo Knight is very cool, and lots of fun, but if you're going to be using it as an off-tank, I'd say you pretty much have to get Sentinel.

Hey hey! Thanks everyone for the input.

I decided, based upon the past few months in our campaign, and tonight's session, that there's no reason to bend my character into a tank/off-tank. The DM isn't going to look at me like that, so I'll never receive items like that, as such, there's not much reason to dip into Battle Master. Especially when we have a bard/wizard/cleric that can support better.

I'm also a relatively new player and am not keen on tool proficiencies yet, so the Rune Knight isn't quite a great fit (Although of the three classes, I think Rune Knight is the best). The Cloud Rune is absolutely awesome, but most of our important encounters consist of one big baddie, and redirecting an attack isn't too beneficial as the only other target worth hitting is a familiar that is usually dead after the first round.

So, I've decided on the Echo Knight, and will be aiming for a 20/18/18 (Dex/Con/Wis) stat-line.

I think, even though these are not on the list, that you might want to multiclass into champion. I would also add samurai but you're a monk with better things to do with your bonus action. The 3 options I feel aren't really 4-level dips (but I don't have many expansion books, and I only got the core books couple months ago). Though I feel a monk- echo knight would be the sickest thing to be in dnd, but unfortunately the clone needs you're bonus action to operate.

Just a sidenote to maybe improve Stunning Strike effectiveness: there is a new magic item in Fizban’s called Dragonhide Belt which increases your save DCs by +1/+2/+3 scaling by item rarity, starting from Uncommon.