I'd suggest something like a Fulltone Fulldrive 2 myself. Very versatile pedal that lets the natural sound of the guitar shine through (imo at least).
I have a Ibanez Tube Screamer TS-9. They are very common, cost about £90 and I really like mine. Stevie Ray Vaughan, used the TS808 which was a predecessor. I think it is very commonly used by modern blues players. There are some people who say it's not as good as earlier versions, I would not know as I have never really heard them apart from on SRV records.
Klon Centaur will do what you want.
Quote from: TwilightOdysseyKlon Centaur will do what you want.booyah!(that's an agreement, by the way. it is a lot of cash though, but it's fricken' awesome.)EDIT: for cheaper:i don't think the ts9 is what you want, the ts808 is better for mellower stuff.the trex alberta is quite nice, as is the black box x-ray.depends on your budget, obviously.