I prefer thicker, but have found that building a lather is a lot like honing a razor. The best edge is just shy of being overhoned. The best lather (for me anyway) is just shy of drying out before completing the shave. Too little water and you will never be able to build a lather to start with. Too much water and it will be runny while providing little lubrication. If the lather is too thick (and dry) before you complete your shave the lather will dry out and it will look like its snowing in your bathroom. At the same time, a dried out lather provides less lubrication than water only!

The proper water to cream ratio? It depends on the cream (and your brush). Some require much more than others to build a lather. Just like razor honing, each seems to require a slightly different touch on the hones to create the perfect edge. Moral of the story...practice, practice, practice. When you finds what works for you, stick with it.

Just another data point,
Ed