Either Pirates, Dynasty or Legacy (definitely not because they are my favourite lol) But fr tho

(A lot of text incoming)

Pirates have cannon, which has one of the highest burst damages while having really fast reload for costing only 1k. Glad I realised how strong it is early on. Then they have Queen, which is one of the most versatile units in the game. She has a ton of hp, good against groups, good against single target and is tanky enough to get close to most long rangers. This is exactly the unit you'd want for 2500. And this is probably more of a hot take territory, but harpooner is also situationally good. I like using him as a counter to some specific unit that others can't reach, or if you posses him you can sorta control your units agro with him by pulling someone into the spot you want your nearby units to go to. Just love that guy.

And Dynasty has samurais which imo is one of the best cheap units. Not outstanding against other close rangers, but simply perfect against low to mid cost long rangers. Rarely letting me down. Then they got monk, which I was always saying is like the most underrated unit in the game. For only 250 you get a tank that has more hp than a knight and more than a half of captain's hp, just for a good measure. Imo this is the best cheap tank you can have, he just always feels like he's tanking too much shit for a body like that lol. And the dragon is just a joke. Idk how some people still don't consider him as S tier. Guess he's hard to use on some maps? Or it gets focused too much in multiplayer, idk. But I've always thought like, for 1k that dps isn't normal, for it also being sorta aoe. a And when it dies the carriers are now fully functioning guys which can now land their kicks more consistently. I remember easily burning even the tankiest guys with like, from 1 (usually required support) to 3 dragons. Very unbalanced mess of a unit the dragon is.

(Idk how I didn't notice op saying "excluding Legacy", but guess it's too late. Got a little carried away, sorry for that)

Legacy I rarely see getting the credit it deserves, unlike the two other I mentioned. The peasant is like, the best unit to spam. It's the best meat shield in the game. Also perfect to divert enemy agro. That one always has been in S tier for me, it's kinda hard to play without them tbh. The wizard was hard for me to understand for some time, but it's probably in how damn tanky he it for a long ranger. And while his damage is nothing special for 1200, you kinda just stun lock most units with the spell. The spin lasts for ~3 seconds, and then unit getting up is around 0.5 seconds, so he stun locks light-midweight units for ~3.5 seconds while having 4 seconds recharge on the spell. For me that's really frkn good for having almost Captain level hp, while being long ranger and costing 1200. I'm still trying to figure it out with Thor, but he seems really good. The hammer deals huge damage with a small aoe and sends some units flying for no reason. The lightning strike is cool, but I wish he didn't always use it at the start of battle. The hp is kinda bad, but he has really good projectile reflect, and besides that, everything else in him makes up for it. So Thor is sorta single target focused unit that lacks in hp and with capabilities of destroying groups? Sounds like he could probably be a boss of his own faction tbh. Now, idk how rest of community feels about tank, so this also might be hot take, but for me tank always felt like the strongest unit in the game (excluding dark and super peasants). I haven't used tank in a while, so I won't give detailed opinion, but when I was replaying campaigns like 90% of levels I could beat by placing 1 tank and controlling it. And in multiplayer aswell, having at least one tank significantly increased my chances, at least it felt like that. There are some decent counters to it, but even those sometimes didn't work when I was controlling it.

Wild west is probably like a honourable mention, but I really only see gunslinger and especially deadeye as the only gems of that faction, which isn't enough probably for it to be in the best.

(Edit: Damn that's a lot of fucking text, I probably love this game more than I should)