I never got the appeal to Star Fox honestly, I mean it was dated before it was released.
I agree in that I find the SNES Star Fox to actually be the weakest game. However, Star Fox 64 gave a better picture of what the series could be and was closer to the vision a lot of fans had about it when it first came out on the SNES and had Nintendo Power comics made of it. I love the idea of space adventures with animals. *GASP* Animal Crossing in Space! That's a genius idea. I must make sure no one steals it....
Back on track, Star Fox is a bit like the Star Wars of the Nintendo Universe. You could make a lot of parallels between the two series. Unlike Mario, it had a history already to it with many characters and personalities and motivations. Rather than go through the whole origins of everything, you just dive into that world and start in the middle of where these characters are.
I guess it's the same thing that appeals to me a bit about F-Zero. You have all these crazy and interesting racers and you wonder a bit what that world is like and what kinds of other stories and histories there are. What other planets are there to explore and see. And the opening cinematic of Star Fox 64 and Star Fox: Assault with the crew assembling to head into battle with the mission type music playing is another little thing that just appeals to me. I want to join up with this crew and head off into spectacular adventures and battles.
Here's the Assault intro again:
I have no idea how many times I've watched that but I still love it. The music, the call to action and the glimpses of interesting Lylat locations and missions. To me, that brief little opening encapsulates why I'm still excited about Star Fox and why I'll always care about this franchise.