Blu-ray is a standard so from the disc and out of the unit (digitally) the signal is the same on all players, the differences are the in-between steps where quality of processors, DACs, etc. can really matter. For mainstream brands you'll want one who is also a reputable chipmaker as it's cost-effective for them to spec it better than a ____. Higher-end brands are usually pretty safe because they make it their business to make sure all of that is properly spec'd (which shows up in the cost, since they don't fab chips internally rather they have to buy them in small lots). Personally, I use a Panasonic and while it is terribly slow to start, the quality is very good.
