Exactly.

Almost 40% of N64 owners had Mario 64. That's a higher attach rate than Halo on the original Xbox.

I agree! DKC could have easily been an early to mid PS1 game.

Insert Mario Kart 8 joke here. 

But yeah, you guys got to the response before I could. SMB is spot for spot the most important game of all time, but SMB itself only becomes impressive as a game when you look at Lost Levels. Otherwise it's just a game, really. (I explain my reasoning in much more depth on my YT review of Mario 1 and LL, but in short: Without LL to show how bad Mario could've ended up with a lesser development team and less of a care for game design, Mario 1 would only be a game to be remembered for its impact, not its quality as a game.) If a game needs a subpar sequel to be impressive in a modern light, then I don't think it's the most impressive one. By that metric, Wii Sports could be the most impressive because it got so many non-gamers to buy in - it's just as true but not in a way any of us would consider particularly valid. Mario 64 directly forced the competition to adapt to true 360 degree controls - Mario 1 had no competition in many regions. 

They're both impressive for different reasons. The way I read the poll question though, I feel 64 wins. Obviously Mario 1 is more important, without it we wouldn't have a 64, but there were serviceable 2D platformers before SMB1 - there were no serviceable 3D platformers before 64.