I'd go with a 7 string. As for which model, I have the perfect thing for you. Find yourself a used Ibanez RG7620... fixed bridge, nice pickups stock and of course seven strings. Best thing about it is...half the time at stores it will be cheap as hell. There really isn't a big interest in 7 string playing anymore, I got mine for $100 at a Music-Go-Round, and I've seen them for that little at other places.