BttF 2-3 are not bad, although 2 is embarassingly and humorously dated.
Avoid the Matrix sequels. IMHO they are not satisfying and actually degrade my enjoyment of the original. Reloaded has some cool action sequences but there is not much to be said for Revolutions.
The Fly II is not good. Mostly forgettable retread.
I seem to remember at least one of the Revenge of the Nerds sequels was tolerable, but the original is no masterpiece either.
Don’t watch any Fly sequels. There were two sequels to the original 1950s Fly. Whereas the original was on color, with David Hedison and Vincent Price and decent effects, the second was black and white, with abysmal effects (although, amazingly, it stilll had Vincent Prioce). The third, Curse of the Fly, was off-the radar awful.
The remake, by David Cronenberg,was pretty good. The sequel to the remake was directed by the special-effects guy from the remake, with a script by nobiody you ever heard of, and is awful.
For ,my money, the first sequel to The Matrix is pretty good, if you fast-forward through the time- and soul-killing “Zion” section. I think the film boasyts one of the cinema’s longest and most intense action sequences, starting when they walk into the Merovingian’s restaurant/club and ending with the truck crash. The thirs movie is only sporadically interesting, and a big letdown.
The Back to the Future sequels are great, and well worth watching.