So-called "Indie music". They're the bands
that are abandoning the traditional labels in droves already anyway, and their target audience (high-school through college aged kids) are the most tech savvy demographic (and likely to use pure-digital delivery services).
Artists like: Arcade Fire, Apples in Stereo, Arctic Monkeys, Belle and Sebastian, Bloc Party, Blonde Redhead, bright eyes, brand new, Fruit Bats, My Morning Jacket, the New Pornographers, Clap Your Hands Say Yeah, etc.
I'd also try to target lower-volume artists in non-mainstream Genres. Things like Americana, Bluegrass, Classical, Reggae, and World-Music. All of these Genres have significant followings and sales, but they're not mainstream enough to garner real support from the big labels. Many of those artists are extremely frustrated with their labels' level of support and their levels of distribution and are "ripe for the picking". I'm thinking Artists like: Avett Brothers, Be Good Tanyas, Beenie Man, Lambsbread, Old Crow Medicine Show, and Tony Rice (and Classical is a huge opportunity too).
Better deals for the Artists, with increased exposure, could be a potent combination for many of these artists, I suspect.