I've shopped at many, but my favorite is QuiltInADay
https://www.quiltinaday.com/. They have some amazing deals, especially in their clearance. They give an inch extra most of the time for shrinkage. And they TEAR the fabric, so it always comes on grain, meaning that you don't lose anything straightening the grain. And their shipping is reasonably fast.
I've always liked Whittle Fabrics
https://www.whittlesfabrics.com/ for customer service, although most of their fabric isn't my taste, so I don't order from them as much as I would like.
I also have bought from Thousands of Bolts
https://www.thousandsofbolts.com from time to time. They are quick to ship and have a huge selection at decent prices.