The majority of solely action based mecha anime I've seen are utter garbage. So other than Gurren Lagann and maybe Top wo Nerae! I tend to lean more toward more character driven shows with mecha elements.
I think Ghost in the shell willn't count. Althoug there are robots in it, but It's not like Eureka 7, RahXephon or other animes which contain robot fighting. I think you understand what I ment.
1.Gundam (several series, not including Seed)
2.Eureks 7
3.Full Metal Panic!
4.Neon Genesis Evangelion
5.Transformers(I don't really like, I just don't know many Mecha animes)