from a female's perspective, i really don't care one way or the other. ribbed, not ribbed...makes not one difference to me.
however, the whole condom falling off or breaking? scary stuff. there's nothing like realizing the condom's gone or broken to ruin the after effects of great sex.
you know, it's interesting. thinking back on it, the only times i've ever experienced the the condom falling off have all been with a spermicide lubricated condom. that is weird, now that i think about it. (and not to sound like a whore here, but i've had it happen on three separate incidents with three different guys. don't judge me!
this is why i prefer to be in a monogamous relationship where condoms are not used, and also why i'm on birth control myself, and regularly get tested.
and...i just don't sleep around to begin with.