I like my dildo better because I can stick it to the wall or floor!
I have both and would definitely choose my vibrator over my dildo and even more so since getting my new Ovo K2 Vibe, I love it!!
I would prefer both, but if I have to choose, hands down (there) it's a vib!
I think it depends on the situation :P but if the situation is trying to get off as quick as possible then vib...definitely vib, that is if i have to choose. i like to use both at the same time :P