This is my top 10 mecha based animes that I have really enjoyed over the years.
Patlabor movies 1 and 2 are at the top, Patlabor XIII was good but nowhere near as good as the previous two films. The TV series is also very enjoyable, if not rather dated now.
Gunparade March was a little bit of a strange one really. More of a romance than a mecha anime. I really enjoyed the setting of the show but for the love of all that is holy watch with subs. The dubbed version is so bad you will want to pull your teeth out.A very enjoyable watch all in all.
Macross Plus is just classic mecha anime at its best with great music and soild story.
Gasaraki was a nice change of pace from the over-powered super powerful mecha animes that are around. Set in a time when bi-peddle mecha are just starting to be used by different countries military groups. They break down due to sand, slow and cumbersome. With a supernatural twist to the story makes this a definite watch in my book.
Evangelion nothing to really say to that except its evangelion :D
RahXephon is a slightly less depressing version of evangelion with slightly less confusion and more romance.
Argentosoma is mainly on this list for one character Mr.X who's dialogue with the main character is just short of epic.
Blue Genders main character Yuji has the most epic sideburns ever in an anime to date. Also big fricking monsters, violence, sex and romance all rolled into a good story.
Break Blades films from production I.G. Really enjoyed its 1 hour long episodes, animation quality was excellent with a good story. I hope there are more of these in the future because 6 is not enough.
Eureka Seven just made my top 10, not a big fan of the art style but the story and characters were interesting enough to see me through it.