Mobile Suit Gundam (and Z Gundam and ZZ Gundam plus all the other UC Gundams) The older they are, the more episodes they have but it tops at 50 (actually, 49 I think O_O) Most of the other series in the... series are like 13 episodes, 6 episodes... And then you have the other Gundams like G.Gundam and Gundam Wing...
Anyhow, if you're alright with weird nudity, Zeorymer of the Heavens... was partially enjoyable. It's four episodes long so yeah...
Currently watching RahXephon which is pretty weird but at least you have some action... If you liked Evangelion but were disappointed by it, watch RahXephon.
I've heard Gear Fighter Dendoh is pretty good but I haven't started it yet.
Suffice to say, these are all robot shows.