Bread knives are mostly disposable, we recommend just buying a decent one and throw it away when it won't cut anymore instead of trying to sharpen them (it's brutal). Personally, bread knives that have a raised handle and slight curve to the blade work very well.
Tojiro ITK Bread Knife 270mm cuts like butter and can even cut through watermelon with very little resistance. The price is awesome for the value and is great for very thin bread slices and tomatoes. The blade is personally ideal as it’s “wavy” and glides, rather than “toothy”, which can actually tear. Other recommendations: It is by far the best serrated blade I have ever used. I own a Shun Classic(home knife block), Wusthof Grand Prix, & Victorinox bread knives also. The Tojiro out performs all of them for less money.