I completely agree about that. Despite the small increases/high cost, that faction is overpowered. :
Orcs... just orcs. :\ I never considered them the strongest, and I still don't.
The Sylvans have a lot more than just archers. Ogres, those fat guys, imba units... unicorns, druids, powerful meteor showers, and all sorts of other things.
Inferno is weak, has few archers, a large damage range, and suffers losses... but I love them) because I've always had a soft spot for anti-imba factions.
Not many people play as the Wizards, and many don't even like them. But I won't deny how cool they are.
I prefer not to play as the Dwarves... runic magic greatly compensates for the overall weakness of their troops.
Corrected) Necropolis. It's strong and has a large army, and it's immune to various effects like Mirror Image or Hypnotize. I just don't like it. I'm tired of it. Everyone plays as that faction.
Heaven. Those who don't play as the Undead play as it. It's strong. Just archers, cavalry, and griffons. And they're all just strong. It's a very primitive Castle. It has few tactical options. Besides flying into the sky and calculating the number of squares for the Paladins to run, the Gray Warlock doesn't really have to think much.