Ahh.. Man, what started it all was Starfox 1, the one that was released for the SNES, that had some fairly decent replayability, plus it was fun, and at the time it was state-of-the-art. Starfox 2, the unreleased version for the SNES would have been better than StarFox 1 if they touched up on it, kept co-op, and fixed the bugs. Starfox 64, hands down, public opinion, and mine, say it's the best StarFox game EVAR. Adventures was delayed and didn't have the best gameplay ever, but the graphics, the somewhat intriguing storyline, and the puzzles were actually pretty fun. THough, the lack of flying around a lot was not. Assault was actually pretty good and I still play it from time to time, especially with friends. The multiplayer in that game is actually pretty fun. Command, is a step in the right direction though! Great replayability and it doesn't seem repetetive suprisingly. The different amounts of ships, the levels, the storylines, and the music! It's what StarFox2 should have been, minus the co-op part, and that's probably why it was more successful than one would think.
Just threw in my opinions here.