SOG - They used to be a heavy hitter. Never huge, but they were on par with Benchmade, Spyderco, Etc.... for many years back in the day.
Al Mar - Not so much out of favor, but they just don't release enough knives or have a web presence. Would love to see a retro line.
Outdoor Edge - They made/make interesting, quality stuff, but never pushed the cutlery market seriously.
Timberline - In the 90's - early 2000's, they were an interesting brand, now :shrug:.
Gerber - Getting better, but the last 15 - 20 years were mostly
.
Puma - They still sell some interesting models, but it's a shell of it's former self.
Marbles - Wish this could get reinvented as a boutique brand. They still have the Chinese lines, but you don't even hear about them much in comparison to Rough Rider.
Camillus - I'm pretty sure most consider it a dead brand even though they sprang back up.
Randall - Not dead or unpopular, still very strong in fact. But it has taken a little hit compared to the wild highs of years ago.