I no longer like HoMM because of infinite unit stacking, no unit maintenance, and no fog of war (only visible vs unexplored). Those things feel really dumb to come back to after playing the other games.
Eador - Good, but ultimately the hero grinding is not to my taste.
MoM is great, but no MP, so I don't play it.
AoW I play a lot at the GoG forum, and I even make maps for it. It has the best scouting/killing enemy scouts dynamic, ie vision game, of the games in this post. And it has a few little things like fire immune units walking on lava, ethereal units killing any number of troops if they have only mundane weapons, flying ranged attackers killing any number of walking melee troops, walled cities being uncaptureable unless you brought something that can break walls or climb/fly over them, and so on. You can make a three-layer map (two cave levels) with one-way teleporters and crazy stuff like that. Or if an enemy army is crossing a river of frozen ice and you fire a Fire Storm onto it, they drown. I didn't get bored of this game when I got into Dominions 5.
Dominions - totally btfos all the other games, even MoM, on mechanics. MP is good, lore is good. Relatively weak on aesthetic (mind blast sfx reeeeeeeee) but I still like its sprites and music anyway.
So for me it's a toss-up between Dominions and AoW.