My go-to's: Top Gun Supply, SG Ammo, Midway USA, Safariland, Gov-X.
Locally, my Bi-Mart still advertises .223/5.56mm and all handgun ammo, still sells all kinds of guns. Bye bye, Wal-Mart.
Also locally, have a Tractor Supply Co. and an ACE Hardware that still seem pretty pro-gun. And well, I still like Cabela's and Bass Pro for lots of stuff, see a lot of folks bashing that company hereabouts.
Then there's Ranch and Home in the Tri-Cities, freakin' awesome.
MagPul,
5.11,
Maxpedition,
Tactical Tailor all constitute a fair amount of my kit.
Always had good service from Brownell's,
Hogue,
VZ-Grips,
Proven Arms & Outfitters (Quantico Tactical),
Vortex,
CDNN
For me, it's all about reasonable on-line pricing, shipping fees, speed of delivery, good customer service over the phone or in person, but most of all, gotta demonstrate a solid pro-2A philosophy.