I've just dinished trying out a new polyurethane product. I used to use Varathane way back when, but when I ran out of that I looked in my husband's Fine Woodworking magazine and they rated Olympic as being much more scratch-resistant, so I got a pint of that and used it until it ran out (about 3 years). But with both Varathane and Olympic I used to have trouble getting a good, smooth, brushmark-free surface. Sometimes it would "creep" as it dried if I thinned it down; there was a very fine balance between being too thick and seeing brush strokes and being too thin and getting creep. So when I ran out of Olympic, I did some more research, and found a product called General Finishes High Performance gloss water-based polyurethane, sold at the Woodcraft store, which had consistently high reviews, so I bought a pint.
I can heartily recommend this product. I've used it for both round and flat pieces, both dip-coated and brushed on, and it gives a beautiful even coat. I've found you can get a virtually perfect surface on a flat piece by flowing a thick coat on and letting the excess drip off; it dries evenly without contracting or crawling. The control piece I made using Olympic looked so lousy next to the General Finishes one that I strained the Olympic through a piece of pantyhose and re-did the control, thinking that it must have picked up some particles. If you like a very glass-like surface and are having problems with visible brushstrokes, you might want to give this a try. It's expensive ($16.50 per pint) but worth every penny in saved time. - Beth C