Edit: Correction. Just forget I said any of that. Lehrer has it covered and in a much better language style than I had.
As for your choices. Ultimately it is up to you and what do you think is fun? Because the reality is that anything you add is going to be one of two things.
It's either going to mesh with the monk somewhat but but rather weak because it's only 1 or 2 levels of it.
Or it's going to be something that clashes with the monk but be just a bit more powerful than absolute baseline (such as the cantrips from several of these choices).
So at the point. Pick what you want to play and you think will have fun with and won't hold your style of Monk and your fun at playing back too much or at all. Because that's really the choice your making at this point.
Multiclassing is really not the power house that many people make it out to be and it's particularly not such at Tier 4 of play. It gives you a bit more but objectively there is nothing better about it because a lot of it is baseline when your talking about end game. you could even pick up a level of fighter for Action Surge and this still would be true because while Action surge is powerful. It doesn't often do something dramatically significant at the high level of play. It's just another bit of burst much like smiting, or backstabbing or certain spells.
In the current (but ending soon) campaign I'm in I'm playing a Way of Mercy monk that dipped into the Peace Domain Cleric for 2 levels and it's been really interesting and unique. You're no Cleric or Paladin, but you are this weird and interesting attack support that's always helping the party thanks to Emboldening Bond (which is tied to proficiency, so you can easily cover the party.), some useful cantrips like Guidance (which stacks with Bond), and Sacred Flame, a couple of good spells...Shield of Faith always useful, Protection from Evil and Good can be good in a pinch, a few other choices...Sanctuary can be useful in a pinch to help a party member who needs a moment out. Way of Mercy is no slouch on damage (in fact I think it's one of the currently most damaging of the Monk subclasses, despite being the quasi support one, which is really weird.)...you could even take magic initiate warlock primarily for Hex, and on a hexed target...a full extra attack/flurry combo of four hits+hand of harm+1d6 on each hit=like 9 dice being rolled for a single turn, which is pretty fun. Plus all the Stunning Strikes.
But then, you could break from full damage to offer some on the go healing to both yourself or party members with some Hands of Healing, heal some basic ailments, and if you take that 2nd cleric level, your Channel Divinity allows you to run around and heal for 2d6 + your Wisdom modifier and because of Monk's inherently high movement speed you can really get around. I did consider going 1Cleric/1Barb too just for Rage's damage mitigation+Tough (which I took anyways) to become a self healing pseudo punch tank too which sounds fun.
It's a weird combination but it's been pretty fun and unique.
Level 1: Fighter, unarmed fighting style (d8 for unarmed attacks at level 1), and prof in more weapons for 2nd level monk ability
Level 2: Arcana cleric: now you have ranged cantrips! Plus... bless, healing word, and BANE to make stunning strike work...
then go monk X ( I prefer shadow monk with eldritch adept and devil's sight)
GishLife
Of these, I'd probably go Light Cleric.
In the current (but ending soon) campaign I'm in I'm playing a Way of Mercy monk that dipped into the Peace Domain Cleric for 2 levels and it's been really interesting and unique. You're no Cleric or Paladin, but you are this weird and interesting attack support that's always helping the party thanks to Emboldening Bond (which is tied to proficiency, so you can easily cover the party.), some useful cantrips like Guidance (which stacks with Bond), and Sacred Flame, a couple of good spells...Shield of Faith always useful, Protection from Evil and Good can be good in a pinch, a few other choices...Sanctuary can be useful in a pinch to help a party member who needs a moment out. Way of Mercy is no slouch on damage (in fact I think it's one of the currently most damaging of the Monk subclasses, despite being the quasi support one, which is really weird.)...you could even take magic initiate warlock primarily for Hex, and on a hexed target...a full extra attack/flurry combo of four hits+hand of harm+1d6 on each hit=like 9 dice being rolled for a single turn, which is pretty fun. Plus all the Stunning Strikes.
But then, you could break from full damage to offer some on the go healing to both yourself or party members with some Hands of Healing, heal some basic ailments, and if you take that 2nd cleric level, your Channel Divinity allows you to run around and heal for 2d6 + your Wisdom modifier and because of Monk's inherently high movement speed you can really get around. I did consider going 1Cleric/1Barb too just for Rage's damage mitigation+Tough (which I took anyways) to become a self healing pseudo punch tank too which sounds fun.
It's a weird combination but it's been pretty fun and unique.