I was a big fan of the cartoon when I was a kid, but aside from a few quality episodes (e.g., Webworld), it hasn't held up very well for me. I still own the old movie and give it a watch every now and then for all the awesome one-liners.
At this point, I'm a much bigger fan of the old Marvel Transformers comics. They were generally darker than the cartoon (there weren't too many cartoon episodes like the string of comics that saw Shockwave blast up the Autobots, hang them from the ceiling, decapitate Prime, and seize power from Megatron by pummeling him) and made some very memorable characters out of certain Transformers (Shockwave, Ratchet, Blaster, Scorponok, etc.).
Robotech is an old cartoon I can still appreciate and enjoy.