I love the 1990 film. I was 8 when it came out and the exact target of the TMNT obsession back then. I watched the cartoon religiously and had a bunch of the toys (I remember the actual four turtles were hard to find for a while when the film hit).
That one still holds up-- I love the story and characters, and in retrospect I like that they based it primarily on the old comics with a couple of nods to the cartoon (Like April being a reporter). I also thought Judith Hoag was great at playing that hard-nosed reporter role very well. And the legit martial arts with the Foot Clan and especially Shredder is great.
The sequel, which I loved even more as a kid, is horrible to me now
I can watch it every great once in a while out of nostalgia, but it's so much cheezier and sanitized for kids. Doesn't hold up well.
And of course the third film, which I call the Chuck E. Cheese animatronic Turtles movie, is beyond bad. I had just about grown out of the turtles when this one came out, and I can't help but think the awfulness of it had a hand in that.