Many of these are not underrated. Jet Force Gemini was a huge Rare title at the time. I also think it's a bit shit, but that's besides the point. Blast Corps is also pretty popular in the hardcore circle.
There is a VAST C-tier library on N64 that goes largely unappreciated. Games like Buck Bumble, Battle Tanx, Hybrid Heaven (incredible cinematic presentation for the time), etc. Those were some good fun.
My Man! I would kill for this to hit Wii U VC sometime. Going to throw out Gauntlet 64, its a fun game, especially the more players you have. Also a shoutout to mischief makers, because the game is so awesome.
The game was influenced by Metal Gear Solid and, in turn, WinBack's cover system eventually went on to influence several later shooters, including Metal Gear Solid 2: Sons of Liberty (2001) and Kill Switch (2003), which in turn influenced games like Gears of War (2006). The cover system has since become a staple of third-person shooters. WinBack also featured a laser sight mechanic that was later incorporated in action games such as Metal Gear Solid 2 and Resident Evil 4 (2005), and in turn would also become a staple of third-person shooters.