I'm partial to E. Guittard. It's the only really good one made in the US. Guittard is mostly on the industrial end (they supply See's and many others), but they do have a consumer line. Very much worth checking out (www.guittard.com).
For imports, I really like Valrhona, Callebaut, and Bonnat. Look for a manufacturer that makes couvertures and you'll get a handle on the good stuff. There's a whole different world of chocolate that you rarely find on store shelves. It's like thinking that the only headphones available are the ones at BestBuy.
Avoid the "specialty" manufacturers of überexpensive chocolate. Many of them don't actually manufacture chocolate. They buy couvertures from companies like the ones mentioned above, melt them down into forms, occasionally make confections, etc., and charge you an arm and a leg. You'll also pay a lot for a fancy box.
Hmmm... that somehow sounds familiar, doesn't it? Anyhow, the good stuff isn't the cheapest, but if you hit up a company like Guittard, Valrhona, et al., you'll get the highest quality at the lowest possible cost.