I know that both at some point were comics made by Marvel and that Thundercats was animated by a japanese studio and Transformers had an original series in japan but was here in america first. That's the info I have but what is what? And please no guessing if you don't know please don't play favorites between american and japanese cartoons, ok?
Transformers was animated by an American company whom employed Japanese animators, Thundercats was made by Toei who is a Anime company but it was made for Americans.
Transformers was an American production but it had some helps from a Japanese studio. It is like this until Headmaster which is a 100% Japanese production. The last US Transformers US made are Rebirth which came out in fact after Headmaster.
