besides my list of:
1) Warriors especially with copper weapons or even without (could use some more hammers to build like +5 or +10 with scouts keeping their cost)
Anyone doubting that warriors are one of the most overpowered parts of the game: take a peak at the thread about the ljosalfar survival challenge (depicting that axemen are not worth it in direct comparison). Its also viable for almost any civ.
But maybe at that part of the game its fine and perhaps it will indeed be "fixed" if the AI is impoved further. So a direct nerf might not be the best path.
2) Power of stack busters in general at least whitin the limits these spells have now including tsunami (and thats very much arguable but i for one think they are.). But thats not by a big margin imo. Certainly not as serious as Warriors.
I don't know anything else which is in the realm of really problematic overpoweredness which makes other options in the same field nonviable.
Edit important addition: Apart from that AI nonability to cope with FFH 2 might be the most serious problem to balance anyways and if improved further might very well make many of the existing balancing issues moot.
I rather think that there is a bigger problem (apart from AI improvements) with things beeing underpowered or uninteresting right now like:
narrow gameplay for grigori (with councils missing mostly among other things, Archmages / Luonotars or early Warrior / Scout heroes (and early upgrades of them) are a bit few to make them really intersting and fun to play)
Elhoim lacking the spiritual trait or something else to make them on par with others,
Doviello in their current form (i guess thats the civ that will change with 0.33
),
mercantilism civic and compassion line civics (perhaps a small boost for aristocracy might be in order as well),
overpricedness of archery line (especially boyers and accuracy, also very bland units and an economically uninteresting tree) and high-end melee techs (beyond mithril weapons).
One of the ways to improve gameplay imo whould be to balance the crass difference in value of techs / improvements of the early game (like allowing chopping / cottages and other things earlier with some considerable drawbacks / without nerfing the existing options. Like discussed with some rather interesting ideas in another thread)
Those options are not really overpowered but early game whould still improve with earlier acess to some of those.
And while i have no real problem with reading people complaining about features beeing to powerful in itself, i do dislike the attitude of proclaming something without even remotely backing it up with anything just because of some undefined gut-feeling or because nothing else of simmilar power is known to some rather new FFH2 players which lack much experience with the mod as a whole. (Thats far from the rule but it still seems often enough to be very noticable.)
And seconding jumping on a wagon just for the sake of agreeing without putting any effort as to why or adding any insight into the matter.
In so far i agree with the op that this conclusion is jumped upon far to haphazardly and with so much vigor if placed elsewhere it whould greathly improve the mod (much more then adressing some of the rather minor balance issues which are left.).
If for example said posters whould instead focus on making suggestions for AI-improvements or events FFH 2 might improve way faster and more substantially.
And while the team has done a terrific job on not heeding any call to nerf here and nerf there / following their own plan / guidlines sometimes those inquiries lead to sad results
(like making Grigori a rather uninteresting if not weak civ or nerfing slave trade to a point where it becomes barely useful.)
And even if those things are indeed nerfed over the top the calls to nerf them even further just don't die (like seen with slave trade.). So perhaps cut it completely? Because its power is over the top by its mere existence? I can't really see a basis for that.
There seem to be quite some players around here which actually seem to be fond of tendious chores which make the game more of a task / less fun and artificially draw things to unessecary length (like seen with critics about the nexus and its unrivaled speeding up of movement / guild of the nine with mountains of gold at hand which are very nice options to speed up gameplay at a point where its not as much of a question wether winning will be accomplished. But not so much unbalancing as just rounding up a game fast. There should be options like these. Since a won game is a won game.
And not everyone likes to end games prematurely or waiting until 100 Units are build in the usual way or moved around to their destination manually.)
Often i think thats down to many players (especially new ones) not realizing that balance is not the top priority with FFH2 design as much as are replayability, outstanding flavor and fun gameplay which are much more of a focus (and FFH2 is all the better for it.
Kudos to the team. Again.).
Or because players think that most of the features are already finished because the game plays so very well they can't imagine it can still become much better featurewise (which is a big testament to the quality of FFH 2). The game is not finished. Wait and see + enjoy.