Random after-hours stalking. Might I suggest taking into consideration size (length, width) if you want a dildo vibrator--bumps, ribbs, and curved are also individual factors. Or if you're going for one of those little finger or tongue ones, take in speed settings, hand-held or "shove it in my purse and no one will find it but me >_>;" sizes.

For both, also think about if you want them to be battery operated, plugged into electrical outlets (I... don't recommend that o.o), or just plain "I'll boil it to sterlize and it's fine." Speaking of sterlizing, silicone's the best, since it won't melt if you sterlize via boiling. But it's more expensive.

Rubber... I'd use soap and water.

... There's also plastics and glass, for both dildos/vibrating dildos/and the little hand helds.

Hope this was helpful. (My speech & typing are jumbly due to lack of sleep.)

~melle