Steam Boy
 

Steam Boy.
I know this one doesn't exactly fit as a "mecha" anime, but it does feature cool steambots and lots of crazy machineries. Plus the art is phenomenal!

have you watched Gundam Wing?

there's plenty more Gumdam series too,Mobile Suit:Gundam and Gundam Wing are some of the best
Burst Angel is a pretty cool one
And there is a great short film called Voices of a Distant Star which you should check out :vsign:

Burst Angel...This series is totally amazing and has it's fair share of mecha fights in it aswell :)

try heroic age

tengen toppa gurren lagann...
it has a great plot and lots of suspense ^^.

mecha recommendations:

- Gundam 00
- Ride Back