I like both a lot, but if I had to pick I'd go with dildos for several reasons. Primarily, it's just a question of sensation. I prefer toys with some give and flexibility, and mechanical parts tend to alter the way a soft toy feels and behaves (which is why I don't go for the "turn off the vibe and use it as a dildo" route in most cases). Besides, internal vibrations are nice, but I prefer thrusting and wiggling motions. And since many dildos aren't hollow, they feel a bit heavier than similarly-sized vibrators, which I like.
It's also easier for me to hold back from squirting with a hand/dildo combo (not that I dislike squirting, but it's nice not having to clean up a wet spot) while vibrators make me squirt almost every time and I can't stop it without also holding back my orgasm.
Finally, dildos don't require batteries or charging, and if well cared for a dildo made of quality materials will last much longer than even the best vibrators.