I stopped playing the Warlords series back at #2. I was aware of Battlecry but I prefer turn based games so I never played it. I never even knew about either of the Warlord 3 games or W4 until I did some searching after this thread came up. So far I'm pretty disappointed with Warlords 4, but there are a lot of warlord combinations to try so maybe I'll find something I like.
I can understand why Infinite Interactive dropped the turn based Warlords for Puzzle Quest, because to be honest it's a really hot title. Galactix and Puzzle Kingdoms not so much. I think Puzzle Quest 2 comes out fairly soon. Maybe they'll go back to a more winning formula.
I can't speak for the Battlecry series, but the turn based Warlords series has simply failed to innovate. I would much rather play AoW. The combat in Warlords was always the weak point, but in W4 they spent all this time on the 3d models and the animations but the combat is barely better than it was in W2. What a waste of resources and effort.