The 80s one is classic. It’s also doofy , the jokes are cheesy and the animation isn’t always the best. It’s a cartoon from the 80s, you gotta set your expectations. It’s still fun though.
The 03 show is the one I remember the least. Probably because I was in diapers. I remember it took itself more seriously, but was still pretty fun. This version of Shredder looks badass tho.
IMO the 2012 series is the best one. It mixes elements of the shows (and even comics) before it in a way that both respects the series heritage while adding new spins on old concepts. It’s a lot of fun, it’s got rad character development. IMO it’s the quintessential turtles show. Tbh though I feel like it drags a little towards the end. I think you should start with this one.
Rise, I’m once again unfamiliar with. It tries a lot of new things, some of them work. Some of them don’t. The animation is stellar though, especially on the fight scenes. And the characters, from what I’ve seen, are pretty funny and enjoyable. But as this is the biggest departure from the turtles formula, I feel it’s best watched after seeing some classic turtles first. But you can do what you want.