Sorry I did not see this post until lately. The water-based is the best to use as it will dissolve and washes off easily, not the same with the oil-based.

One of the best brand is Astroglide (available at Walgreen, CVS,...or any other pharmacy). It comes in a few versions, but my lady's most requested one is Astroglide Gel. Still water soluble but but lasts fairly well and is smooth.

Give it a try!

Cheers.