While I'm no pro mechanic, I've been wrenching on stuff for years. I have a mix of everything, but I have my favorites. Some stuff is better than others. Here's my experiences:
Craftsman: Like others have said, their quality has suffered in recent years. For example, a few years ago, I bought a set of gear wrenches from them. They are awful! The gear mechanism is clunky at best and binds up or freewheels when you need it. No, I'm not cranking on them either; they have been like that since new.
Kobalt: Not bad at all! I have a few socket sets from them and some other tools. I picked up one of those "XTREME Access" socket sets with the pass through sockets on clearance a few months ago and they are really nice to have for a "keep it in the trunk" set.
Harbor Freight: Depends on what you get. Some stuff is great (like their hand wrenches and sockets), and some stuff is just ok (like the file set I have were the handles fell off a few of them). I'd say better than Craftsman at this point. I have the "Earhquake" 3/4" air impact from them, and it's been pretty good.
Husky: I have some Husky ratchets and sockets that are about 20 years old now, and they keep on going. I dig them just fine.
SK: LOVE them. I have a 3/8" drive set from them and a 3/8" drive long handle flex ratchet that's probably my favorite ratchet of all time. They are my go-to set of ratchets whenever I'm working on something. They have put up with a lot of abuse over the years and keep on going. I did, however, crack one of their sockets once. I was pounding the thing on a rusty bolt with a small sledge. Any socket would have cracked.
Mac: Hit and miss. I have some air tools from them (air sander and 3/8" air ratchet) and they have been great. My dad, however, has a ratchet set (1/4" 3/8" and 3/4") and they suck big time. They have a very fine tooth gear, and they always switch direction while ratcheting. I also have some allen sockets from them, and that's a prime example of paying extra for small stuff. They have been great over the years. I've had similar sets strip out on me from lesser brands.
Duralast: Surprisingly good. I have a few sockets, pliers, and screwdrivers from them, and they have all been really great. I don't know who makes them for Autozone, but they are good tools.
Snap On: Good but pricey. But you already know that!
GearWrench: I really like their stuff. Affordable, works well, and you can get it at Advance and a few other places. When ordering at Advance, make sure to do online store pickup and get stupid amounts of money off!