Dreamcast
PS1

Dreamcast one, easy.

PS1. That sound brings back so many memories.

Original Xbox.

Easily the GameCube one.

Top 5

1. Game Boy Advance SP
2. Playstation
3. Gamecube
4. Dreamcast
5. Saturn

of course its the PS1. for me at least. I personally think sony should do an easter egg type thing for the PS4 and give you an option to start up the console like it were a PS1, albeit in HD

As others have said, Dreamcast, OG Xbox, PS1 and Gamecube ones are by far the most memorable ones. If I had to pick just one, the PS1, because it resonated strong in me when I was a kid. Xbox would be a close second, since it was the console I owned.

This is shocking! You all need to get Sega Saturns just for the glorious startup animation. It was amazing.

A hundread little pieces floating about and coalescing into the logo finishing with a sun light effect. It was like you really were traveling to saturn when you turned it on.

1. Saturn
2. Gamecube
3. PlayStation

I wish they would do one for PS4. It could draw inspiration from the video teaser they did for the PlayStation 4 reveal in February of last year, with the blue lightning. It would surely turn out amazing! And it needn't even be too long, 4 or 5 seconds would be enough.