I use Discount Tire. My only thing is they never seem to be able to repair my flats, always seem to have to replace. Maybe I'm just unlucky.
I will say, I got a flat on my new truck and they claimed it could not be repaired. It was going to cost me an arm and a leg to replace, however, they happened to get my same tire in as a trade-in from someone buying new. Still had lots of tread left so got one at a reasonable price and switched it out as my spare. Saved me a couple hundred bucks.