I like to use the model master and polly scale waterbased paints.They leave better detail on the model as the paint is thinner. Its also easy to fix any mistakes as the paint is very thin and is removed with out alot of wet sanding
The oil baised paints will have a deeper shine than the clearcoats used with the waterbased but I still like the water based better.In the end if you want a used look to a model waterbased is the way to go, if you want a showroom finish stay with oil based
Here are a few examples
the yellow and green Mack are waterbased paints
the white and cabover macks are oil. you can see the sheen better with these.
Edit: I should mention that these were all air brushed models. you really cant get a smooth finish with a paint brush with either paint.
Trent