Mecha Anime Recommendations

I'd like to ask all the mecha fans out there: what classic mecha anime would you recommend?

I just finished watching Gundam SEED. Although the plot is a bit cliché, the mecha designs are really cool. I'm looking for something similar to watch next.

I prefer Real Robot series; I'm not really into Super Robot ones. Are there any hidden gems you could recommend?

Thanks in advance, everyone!