I have ordered from Sakura in the past -- they have a huge selection from a variety of manufacturers. I've also used Century -- I like some, but not all, of their products. I'm fortunate in that we have two MA stores in Toronto on the same street -- CKT Sports and Warriors, so that I can actually try stuff on before I buy it.
I visited the Century MA showroom, which is just outside OKC, OK, and that was pretty cool. One day I wouldn't mind visiting AWMA, which is in Philly.
I suppose it depends on what I am ordering, I seem to pick and choose from different suppliers, AWMA (Asian World of Martial Arts), Century, and Masterline are the three major suppliers that we deal with in our dojang.
I like Title MMA http://www.titleboxing.com/ Though they used to be strictly boxing supplies, they have expanded to offer MMA training gear, pads, gloves, heavybags etc.
When it comes to pads & focus mitts, I just purchased some Ultra Fight Gear from Master Toddys. I'll tell ya what, UFG has some really good heavy duty stuff.
Depends on what you are buying. The best wholesale prices on karate uniforms with reasonable quality are offered by KI International. Meanwhile, Century and AWMA offer a wide selection of low to medium quality gear, uniforms, and training aids both at retail and wholesale prices.
I also use a number of specialty vendors for handcrafted weapons depending on their current stock. I also buy Shureido uniforms for myself from RyuKyu Enterprises, the US distributer for Shureido.
I have used Karate depot, Asian World and Century. Now I have a Wholesale account with Century so I anticipate using that the most. I liked karatedepot alot when I was teaching in Iraq because of the $2.00 shipping anywhere, including APO addresses.