Well, Armageddon was a popcorn flick. Deep Impact was supposed to be a serious flick. Armageddon is a bad movie that succeeds at being bad, its biggest failure is not realism but the inability of the director to get something out of the cast. Deep Impact fails at being serious and also underuses its cast, which makes it the worst of the two.
Asteroid... Seen it on TV. Tons of fail there as well.
Now, there are bad movies and bad movies. There are bad movies which are just bad, and bad movies which are so bad that they're good. By this I mean that there is a bad way to be good and a good way to be bad and... Er, OK: most stuff by Antonio Margheriti (aka Anthony B. Dawson) is bad but is good as well. So are many exploitation movies. But it's one thing to do a movie that's just supposed to be fun and making a movie that's supposed to be serious.