I've watched both of them and love both of them to bits. I'm extremely familiar with both of them, love them and all their reincarnations and that is all I can say on the subject without an explosion.
I kinda have a grudge going on with the old 4Kids but they've gotten better. Ontopic: I didn't like the 4Kids dub of Sonic X, I used to love TMNT to pieces when I was a kid though.
Used to watch them. And then I grew up. XD I never cared for TMNT. And I just stopped liking Sonic. PEROID. Offtopic rage: I hate how they try and make those stupid songs! Honestly, I prefer the old 8/16bit songs on the Sega Genesis. They ruined Sonic because they tried too hard to make it "cool". Now, it's a little kid's game.