Digimon.
Well, that's a bit of a loaded answer. But the English dub of the first two seasons is legitimately awful, plus it just seems rather low-budget in many areas in general, and yet I still love it. Partly for the nostalgia, partly for the absolute hilarity of how bad the extra puns and quips they added in can get. The third season is actually pretty good from what I've watched so far, though (I saw a bit of it when I was younger, but never really followed it even as much as the rare times I saw episodes from the first two seasons); Much better English dub along with overall higher production values and vastly improved pacing. I still quite like the 'films' associated with the first two seasons though, even without the filter of nostalgia and punny goodness.
The Star Wars prequels.
Phantom Menace is actually one of my favorite Star Wars films. The other two don't hold up nearly as well outside of the action sequences, but I do genuinely think The Phantom Menace is a good film. I don't care enough to justify it though, I've seen and had those arguments far too many times.
Oh, also the Abrams Star Trek films. I'll admit I don't really care about '09 Trek because I can't remember most of it, but I thought Into Darkness was pretty good and a very fun watch. I'm a heretic because of it, it seems, as no self-respecting fan of TOS would ever like Into Darkness, according to the internet.