No, not really.
Dog Day? Godfather? The Master? Network? Glengarry? Jesse James? There Will Be Blood? Hell, Lebowski?
I'm not saying you won't find a mediocre (or maybe even bad) performance in there the farther down the cast list you go, but to say the line being drawn is arbitrary when you're trying to compare Michael Biehn playing Michael Biehn, Bill Paxton sweating hot dog juice, Goldstein sneering at everything, and Reiser smarming all over the place? And those are the BEST performances aside from Weaver's (which should have won the Oscar that year, absolutely)?
Up against Cazale, Brando, Keaton, Pacino, Caan, Duvall? Hell, I'd argue Abe Vigoda turns in a better performance in Godfather than almost anyone in ALIENS. It's a weird as fuck comparison to make, and one I wasn't expecting to consider (this place is great) when I woke up this morning, but ALIENS is a classic because the performances slot in perfectly to the action/horror engine Cameron built, not because the performances themselves are any great shakes outside of Weaver.
ALIENS is a classic, yes. There is no way it belongs in a discussion of "The best acted films of all time."
It might not even make the top two best acted ALIEN movies of all time, honestly.