Glock, because they make a simple, reliable, effective pistol with widespread market acceptance. It's a quality gun at an affordable price. Spare parts are commonly available and cheap, and one can do their own parts replacements with a basic understanding of the pistol. I had one part break on my Glock (the takedown lever fell out, causing the takedown spring to fall out too -- didn't impair functioning, and cost $5 for parts and shipping from Lone Wolf).
Springfield, for similar reasons to Glock (I own an XD-45). However, spare parts are not available for many parts, which is a bit annoying. Still, their excellent warranty and fine pistols (even if they do just import a few, rather than design them themselves) and rifles are quite good.
Ruger, for making affordable .22LR rifles (such as the 10/22), as well as excellent revolvers, rifles, and autoloaders. Spare parts for certain guns, like the Mini-14 aren't available, but 10/22 parts are everywhere.
Kel-Tec tries their best to make new and innovative products, and they usually do a good job. When they don't, they make it right. I had a firing pin break in a SU-16B, and they mailed me one the next day and it arrived a week later (FL-->CA). No cost to fix.
Remington has made excellent and consistent brass for all my reloading needs. Their rimfire stuff works very well in my 10/22, and I've written to them to thank them for their excellent products, and they took the time to write back and say "you're welcome".
CCI makes great primers and ammo, and I've never had any issues with their primers at all. Zero failures to fire, which is nice.
Federal makes "American Eagle" ammunition which I consider to be the "gold standard of FMJ ammo", and all my comparisons of ammo are made in relative to AE. I have never had a problem shooting American Eagle in centerfire pistol or rifle cartridges, and only a few failures in rimfire (but none recently out of about 2,000 rounds...impressive).
Bushmaster makes excellent ARs, has excellent customer service (I had a slightly canted sight, and they paid to have the rifle UPS'ed back to them, fixed it, and UPS'ed it back to me for free within two weeks). Their ARs use standard parts and components, and can be readily replaced, repaired, or tweaked by anyone.
Lee, for making affordable, effective, and overally quite good reloading equipment. I've saved untold amounts of money using Lee dies, presses, and equipment...and I see no real difference in accuracy or performance compared to similar rounds made on different brand presses.
Powder companies. It's gotta be tough making smokeless powder, particularly when a spark or flame could be devasatating. That, and working in today's political climate makes being in the powder making business somewhat of a challenge, espescially when one targets the relatively small number of reloaders. I applaud IMR's manufacture of consistent, reliable, and clean-burnign powders, and hope all the major powder companies stay in business. Without them, shooting sports would rapidly grind to a halt, even for folks who didn't reload.
Those are the only gun companies I can really comment on...most of the gun companies I rarely have dealings with due to the reliability of their products. I think more and more companies are increasing the quality of their products and reliabilty is getting better.
