In reply to Oogachooga:
Start off with the brand that fits your foot best, and then narrow it down to the model.
La Sportivas generally work for me - I use Muira VS on limestone the most, so would get my "one shoe to do it all" recommendation, but also hard to go wrong with Solutions. Their no-edge shoes are also mostly very good, but occasionally entirely defeated by polished holds where an edge would find a nook to take advantage of, so I wouldn't say they're the best if you only want to carry one shoe.