http://en.wikipedia.org/wiki/B't_XMy favorite mecha series. It breaks quite a lot of standards in mecha anime, too.
It shows you don't need to have 100 meters tall uber-monsters fighting each other for the battles to be good.
And you don't need 190 episodes to get the plot across.
And the main character doesn't need to be a grim, sturdy, experienced, woman-hating a*****e. And he doesn't have to be a newbie who never fought a single battle and wins the first 30 fights on sheer luck and because he has 200 more soldiers around helping.
All in all, the show is good, the manga is good, X is downright the funniest mecha ever created, and even the characters you're supposed to hate end up making you like them.
Bad things about the anime? It only shows three of the seven Demon Generals. The best three, but still, it's a bad point.
And heck, one just has to respect Fou Lafine. Anyone who can kill people by hanging them with a violin chord, and show no emotion at all while doing so, rocks.