On a whole-market level, I'd rate the top 3 as:
1. Wii Sports (Wii)
2. Super Mario Bros (NES)
3. Tetris (GB)
I can't really rate it on a personal level, as the Wii is the only console I've ever gotten near launch. The game I got my PS1 for (Xenogears) was not a launch title, nor technically was the game that I got my PS2 for (FFX). I got my GBA SP long after the system launch and didn't get any title older than LttP for it. I guess Super Mario 64 DS counts for my DS (and I did play it quite a lot). My PSP's initial line-up of games was a total joke before Valkyrie Profile came out. And I do remember Super Mario Bros being our most-played NES game back in the day.
So... I guess if pressed, my personal favorite for a launch title was Super Mario 64 DS, even though that wasn't the game I got my DS for (Dawn of Sorrow was).
Sky Render - Sanity is for the weak.
