Horned God is probably the single most powerful T4.
Well Golden Dragon is but you hardly ever see those.
And Warlords need time and space to get rolling, so if anything larger maps favour them.
Agreed on the campaigns. The original actually got harder after the patches because the AI got some boosting post release.
And Gryphon Riders are…my favourite the unit probably (maybe Knights actually)
They’re mobile and quite tough and get the first strike in iirc.
Shamans are consistently underrated but man I find them very tough to deal with in multiplayer.
Edit: it’s been a while since I played “competitively” but my recollection was that Druid was actually overall the most powerful class.