I have been really disappointed by the times I’ve ordered from a shop online (even one that came highly recommended on forums) that I hadn’t previously visited in person. So now I default to a shop that I stopped by on a trip to Chicago once: www.coffeeandtea.com. They have a good supply of the basics (eg English breakfast tea) that are decent quality and very well priced, perfect for everyday tea. For special occasion teas, I was very impressed by a place in Portland, OR I visited: thejasminepearl.com. A lot more expensive but quality to match.
Nowadays I try to make a habit of stopping by tea shops when visiting new cities, and taking note of which specialty teas each has, their price points, etc. I’ve about five or so that I rotate ordering from at this point.