I perfer oil based but then again I mostly use lube with toys and water based is more versatile. That is the only reason I say water based.
ScottA & Majnara:
There are no toys I know off that I can't use my oil-based lube for. Do you know of a material that it doesn't work on? I use it for silicone, glass, steel, aluminum, plastic and even jelly. What am I missing?
Water based are just so much easier and universal to use and apply to all toys and areas of the body. Oil based lubes are generally messier and can't be used everywhere and anywhere as readily as water based. I'm not saying all oil based lubes are bad... but certainly my top choice is water based.