Resident /m/echa bro here(also Obari guy from before), I'll see if I can help.
>>231
Is a good choice. Its by KyoAni from about 2006. Its 12-13 episodes and features a lot of KyoAni's consistency and great artwork. I've always liked KyoAni's style but am always upset they waste it on simple slice of life shows. FMP:TSR is one of the shows where they go out and show off all sorts of great action scenes.
You then have the more recent Broken Blade series, which is a joint between Xebec and Production IG. Its a series of movies so the budget is very high. Though the characters are very simplistic in design so they are not my cup of tea. But the mecha action is absolutely stunning, they really depict the weight and heavyness of giant 20-30m robots stumbling and fumbling about. Its worth checking out.
Shin Getter Robo Armageddon or Change!! Shin Getter Robo Sekai Saigo no hi, depending on how you look at the name, is a very well animated OVA. My favourite scene from the OVA -
http://www.youtube.com/watch?v=J5zjDpYPgLY#t=7m00s - grab the HD remastered releases if you can, the show looks absolutely stunning there.
Another by the same studio is the Mazikaiser OVA, 7 episodes. Also very stunning to watch. Though be wary of the movie that comes after, they shifted over to digital aided animation, whereas the OVA was all cell based I believe, and the movie comes off quite "plain" or "plasticy" like many anime shows do at that time when companies were just switching over to digital animation.
I have not seen Escalfowne, but from what I understand was a Sunrise Studio 2 production, Cowboy Bebop was their last production. I don't know if people know, but people from Studio 2 went on to form their own studio, which we now know as Studio BONES. Hence why BONES's first work was working on the Cowboy Bebop movie. Many of those from Sunrise Studio 2 now reside in Studio B of BONES. Studio B of BONES handle many of their mecha shows(Though Star Driver is by their C studio who mostly do the 'other' shows like Ouran, Soul Eater, Darker than Black etc..). That said, Escalfowne featured quite a few episodes where Yutaka Nakamura worked on, so I believe its worth checking out. In essence its a BONES show before BONES were formed.
One show I've seen pop up often is a TV series called Generator Gawl, its not quite mecha, but it features a dude in a giant suit of armour, so the concept is similar. The reason I see it pop up often is because it has a very talented staff behind the helm, names including Sushio, Imaishi, Yutaka Nakamura(again). See the OP -
http://www.youtube.com/watch?v=z_mjFGym-xI
If you feel you can withstand about 25 episodes of Monster of the Week, then GaoGaiGar is worth a watch. Their stock footage is really well done and at about episode 25, the story really shifts gear and drops the MotW concept. With episodes 29 and 30 probably the best the show has to offer.
One show I hear often about but haven't seen is Giant Robo, I know very little about it but hear its well animated as its also an OVA.
Phew, that took me a while but hope that helps.