I'm playing my first monk at level 3 (a homebrew WotFE derivative, in no way optimized), but I have been considering a skirmishing warlock dip. If I take Hex and Thunderclap (a Xanathar cantrip), that means I have both duel and hordebreaker capability:
1. Hex with FoB to down one enemy quickly (Extra Attack will help this).
2. Storm the group my Hex target is in, Thunderclap to damage all of them (damage scales with character level, extra damage on the Hex target), use Step of the Wind to disengage, and run back behind the nearest tank.
Depending on your patron, you'll get other nifty combat features that give a little boost of healing, debuff, or field control, and if you dip to level 2 you can get at-will level 1 spells like false life, silent image, or a "beast sense" for humanoids.
This build ignores the potential for eldritch blast, which doesn't exactly fit the monk, as EB is ranged and thrives on high CHA (though you still should have at least decent CHA to help your cantrips land), but you can add it onto this skirmish build if you want. Not sure whether Hex works with Sun Soul's ranged attacks, but it should work melee with any subclass.
Now if you want to be super-crazy, get the Magic Initiate (warlock) feat for a cast of Hex every long rest, and multiclass 2 levels in fighter. By level 7 (5 Monk/2 Fighter), you'll have an insta-kill ability of Hex + Extra Attack + Flurry of Blows + Action Surge to deal 12d6 + (6 x DEX) damage in one turn with your bare fists. (2d6 + DEX attack, 2d6 + DEX extra attack, 4d6 + 2 x DEX FoB, 4d6 + 2 x DEX Action Surge.) Granted, it costs your hex cast, a ki point, and your Action Surge, but with only 16 DEX you'll have a nova at level 7 that does up to 90 damage, average 60, even more if you use a quarterstaff. As your martial arts die increases, that nova will grow to 6d10 + 6d6 + (6 x DEX), upping your average by...12, I think. Or you could add a level-1 dip of warlock onto that to unleash your nova once every short rest instead of once a day.
But this post is about alternatives to the striker build. A 2-level warlock dip seems to be the cheapest good alternative if you have decent CHA.
Otherwise, a 3-level multiclass into druid would work well for wildshape, subclass feature, and most importantly, spellcasting that meshes well with your strong mental stat (WIS). It includes prepared spells for versatility and level 2 spell slots for that extra boost of power in higher-level play. Guidance and Shillelagh cantrips, Cure Wounds at up to 2d8 + WIS, Entangle or Spike Growth for debuff, and utility like Goodberry and Pass Without Trace are all really good for a monk build.
In combat, Monks do put out moderate damage numbers. However, Monks do other stuff that can help in combat situations.
Stunning Strike, on a success, can help out many of your party members. Many people have discussed the value added of the Mobile feat for Monks.
What builds have you created that increase the Monk's skirmishing, debuff, or field control capabilities?
"Time is money. Nobody knows how much time they have, but you can always count how much time you spent. So spend it wisely."
I'm playing my first monk at level 3 (a homebrew WotFE derivative, in no way optimized), but I have been considering a skirmishing warlock dip. If I take Hex and Thunderclap (a Xanathar cantrip), that means I have both duel and hordebreaker capability:
1. Hex with FoB to down one enemy quickly (Extra Attack will help this).
2. Storm the group my Hex target is in, Thunderclap to damage all of them (damage scales with character level, extra damage on the Hex target), use Step of the Wind to disengage, and run back behind the nearest tank.
Depending on your patron, you'll get other nifty combat features that give a little boost of healing, debuff, or field control, and if you dip to level 2 you can get at-will level 1 spells like false life, silent image, or a "beast sense" for humanoids.
This build ignores the potential for eldritch blast, which doesn't exactly fit the monk, as EB is ranged and thrives on high CHA (though you still should have at least decent CHA to help your cantrips land), but you can add it onto this skirmish build if you want. Not sure whether Hex works with Sun Soul's ranged attacks, but it should work melee with any subclass.
Now if you want to be super-crazy, get the Magic Initiate (warlock) feat for a cast of Hex every long rest, and multiclass 2 levels in fighter. By level 7 (5 Monk/2 Fighter), you'll have an insta-kill ability of Hex + Extra Attack + Flurry of Blows + Action Surge to deal 12d6 + (6 x DEX) damage in one turn with your bare fists. (2d6 + DEX attack, 2d6 + DEX extra attack, 4d6 + 2 x DEX FoB, 4d6 + 2 x DEX Action Surge.) Granted, it costs your hex cast, a ki point, and your Action Surge, but with only 16 DEX you'll have a nova at level 7 that does up to 90 damage, average 60, even more if you use a quarterstaff. As your martial arts die increases, that nova will grow to 6d10 + 6d6 + (6 x DEX), upping your average by...12, I think. Or you could add a level-1 dip of warlock onto that to unleash your nova once every short rest instead of once a day.
But this post is about alternatives to the striker build. A 2-level warlock dip seems to be the cheapest good alternative if you have decent CHA.
Otherwise, a 3-level multiclass into druid would work well for wildshape, subclass feature, and most importantly, spellcasting that meshes well with your strong mental stat (WIS). It includes prepared spells for versatility and level 2 spell slots for that extra boost of power in higher-level play. Guidance and Shillelagh cantrips, Cure Wounds at up to 2d8 + WIS, Entangle or Spike Growth for debuff, and utility like Goodberry and Pass Without Trace are all really good for a monk build.