SOGs that I've owned and liked:
Tomcat and Stingray folders
Pros: Very solid lockup and robust blades. Never even got a hint that these locks were going to fail. We're talking Spyderco Manix-level lock security.
Cons: Kraton handle scales are terrible idea for pocketknives--keys eat them up very quickly. AUS-6 (it was never 440A, despite what catalogs said--not that it would have made a difference) sharpened easily but lost sharpness very quickly. Blades not at a good geometry for slicing--very thick right above the edge shoulders. Strong, but would crush a tomato versus slicing it no matter how sharp you got 'em. I never tried fully convexing the blades, now that I think of it. Thinner edges would just blunt even quicker, though.
Bowie in SK-5
Pros: Damn it's a good looking knife! Strong as hell (how could it not be at 5/16" stock thickness?) and holds an edge pretty well in most uses.
Cons: Again, blade geometry. Technically, this really shouldn't be listed as a con, as the knife was designed to be a fighting knife, and will slash throats with aplomb and open large, gaping wound channels with its thick cross section. Worth noting, though, that a deep hollow grind that comes out to full thickness so quickly is very poor blade geometry for utility use, or really ANY kind of use outside of sentry elimination or opening packages. Before the stories begin, I'm sure there's somebody out there who's skinned an elephant with one and then saved a child's life with it in an emergency heart transplant. Nonetheless, other blades will run circles around it.
Government and Government Recon
Pros: One of the best general utility fixed blade patterns put out by any production maker in my opinion. Light but stout, excellent blade geometry for cutting, and it came in an SK-5 steel version! I have two, am selling neither.
Cons: Kraton, Kraton, God-damned Kraton. My old soldier, the one that really gets used, is still going strong, but the handle has worn smooth of all its original texturing and is scratched, cut and torn in many places; deserts with all their prickly plants are not nice environments for such soft stuff. Someday I'll cut the remainder off and put a real handle on it.
Revolver
Pros: Decent blade steel (AUS-8 is a climb from AUS-6 anyway) and a very effective saw for its size.
Cons: Having used it to collect some pieces of a newly fallen mesquite tree in New Mexico, I can say that the hollow handle (top and bottom) with those fairly sharp Zytel edges will get to wearing on your fingers and palm pretty fast. Still, it beast the hell out of trying to break the tree limb off.
All of these were from the Japan-made era, and I'll be holding on to them. Not the best knives I have, but I like 'em.
Others I've had and am just not impressed with. Many of the newest SOGs seem to have consistent issues with ergonomics. I'd not say that if I was the only one as it's a subjective assessment, but when none of my friends or coworkers (the knife-oriented ones, anyway) like the handles and all mention "sharp spots" and similar things, I think it has some legitimacy. Other than the Team Leader, my SOGs of the last few years have been the Vision, the Tomcat III, new Bowie in AUS-8 and the Trident--all of which I tried for awhile and then gave away to family. I also haven't been hugely impressed with the Arc Lock in comparison with Benchmade's version. Never had a failure, but a couple of them became notably less than springy in their action over time without really excessive use.