My vote is up there as X-Men.
And you cannot count out the comics for X-Men, the first 3 seasons were all stories taken directly from the comic. X-Men have continued to make toys to this very day, if it wasn't for the current TMNT comic books & cartoon line they wouldn't be making toys now, nevermind the toys stopped getting made for years on end, but X-Men still had a constant release. How about spin off cartoons? more were made of X-Men than TMNT, Mutant X is clearly better than that crap Power Rangers live action show, if anything TMNT is the ECW, made a big break and became a fad, and comes back for no apparent reason from time to time.