It depends on the price range. If you need something economical, and can life with an 8" blade, I can't imagine anything better for $20 than the Kershaw Kai Pure Komachi
bread knife. KAI is the maker of Shun knives, and even though the Pure Komachi and Wasabi lines are cheaper they're still fantastic knives. I always have one in my roll, and one day I lent it to the guy who cuts all our dinner bread at the restaurant I work at. He was so amazed that I've had to let him use it every day since then- about a month!
I also have a relatively cheap Chicago Cutler Kyoto bread knife. It's also an 8 incher, but after a little touch-up it's so sharp it will "tree-top" hair!
The Kyoto line is CC's asian line and is a total Shun ripoff; the look & trade-dress is near identical, but of course they're not VG10 "supersteel." Still, pretty nice for the price if you can find one. I got mine in a block set at Kohls for $125, mostly out of curiousity. At the price I figured it would be a good gift or something to recommend for those who want a set decent knives for about what I normally pay for a single knife.
You'd be hard pressed to do much better for pure performance-for-$ than the Forschner Fibrox 10.25" bread knife.
Forshner is pretty popular among professional cooks. The blades take a very keen edge and hold it pretty well, yet are soft enough to resharpen without much difficulty. The "Fibrox" polymer handle isn't 'sexy' but it's extremely functional and feels great in the hand. $25 doesn't buy much better than this. If you're hung up on looks, check out the Rosewood line. Same blade, fancier handle, not a lot more expensive.
If you want something really amazing, go for the "Full Monte"- the 9" Shun Classic. It'll set you back almost $125 but will cut like a freakin' lightsaber! For under $150 it's truly The King.