I'm the indecisive type, so I'm not sure what my favorite part of the 90s was. But I can tell you that for one of my brothers, it was the Cheetahmen franchise.
I was born late 90s, so I can't be much of an authority, but from what I can tell the Cheetahmen had their biggest relative audience here in the UK. There was still this censorious attitude around the Teenage Mutant """HERO""" Turtles (can't have ninjas in a kids' show!) so having a human/animal team be properly showcased without as many limits was a big draw. The backstory involving hunting, poaching and illegal animal experimentation probably gave it a moral edge that persuaded them to let it through for Saturday mornings without cuts, and that certainly paid off, as it made quite a few little boys into wannabe conservationists.
I happened to be watching an episode I downloaded just to see what the fuss was about, and I saw an interesting credit. "Based on concepts by Vince Perri (Active Enterprises)". Being interested in bad games from years gone by, that was actually a name I recognised, as Active were the publishers of the infamously terrible multicart
Action 52. I was left thinking, what does a shovelware developer from the early-mid 90s have to do with an actually good cartoon? So I did some digging. As it turns out, Cheetahmen started out as one of the many forgettable games that was planned to appear in A52, but some executive saw what a potential goldmine Perri was sitting on and bought the rights off him for a decent sum and a cut of the royalties. I hear he's still living well off that decision. Even though he made one of the most terrible "games" (there weren't even 52 games on it! The last game, "Action Gamemaster" was just a rush through the other 51!) I say good for him.
Incidentally, a prototype version of Action 52 leaked to the Internet recently, with Cheetahmen intact. It's absolutely horrid. To think that this franchise could have been lost to obscurity.... We can thank our lucky stars that Perri didn't follow through with that, as we got an actually decent game for SNES/Mega Drive by Eurocom (and the iconic "Cheetahmen Chase" music in the process).*
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*OOC: similar to OTL's well-known Cheetahmen music, but much more advanced as it was made for 16-bit consoles