I definitely think 4kids had the best version of Baxter. 4kids Baxter was definitely the most cunning and egotistical, he kept trying to betray Shredder but he could never get away with it.
Then later on 4kids Baxter works with Bishop and the EPF, that was a great direction to take his character in. Fast Forward also redeems Baxter where he decides to give up his evil ways so Bishop can make him a new human body.