If you are talking about within the Vallejo line itself, virtually everything is alcohol/solvent free.  There are literally just a handful of metallic colors in the ModelColor line which are in an alcohol base.

Its worth pointing out here that Vallejo's thinner is not really a thinner in the classic sense.  Reducer might be a more appropriate term.  Put a couple drops in your pallet and leave overnight:  next morning you have a translucent blob, almost like a matt medium.   Point being you must shake it before using as if it were paint (if you dont you should see a lump of white stuff at the bottom of the bottle and you wont be getting the whole "mix").