Which gaming system has the coolest startup sequence when you boot it up, in your opinion?

Dreamcast. PS3 in close second.

Gamecube, really like it on top of the nostalgia.

Neo-Geo one is cool too.

Super Smash Bros. Melee
Sonic Adventure 2 Battle
Sonic Heroes
Super Mario Sunshine
Mario Kart Double Dash!!
Luigi's Mansion
Mario Party 4 & 5
Metroid Prime*
Spider-Man 2
Spider-Man: The Movie
Ultimate Spider-Man
Simpsons Hit And Run
SpongeBob SquarePants: Battle for Bikini Bottom
The SpongeBob SquarePants Movie
The Incredibles
WrestleMania XIX
WWE Day of Reckoning 1 & 2
NBA Live 2003
Madden NFL 2004
Need for Speed Underground 2
The Legend of Zelda: The Wind Waker*
The Legend of Zelda: Twilight Princess*

All of these games that defined my early childhood (except for the ones that have an * next to it, because I didn't play them until senior year of high school or first year of college.) They all had one thing in common...

Gamecube 1000%

Nothing else even came close.

PS1 and PS2 are the most nostalgic for me.

1. Sega CD
2. PS1
3. Original XBox

Gamecube, then PS1, then Japanese Sega Saturn. I feel like all of these really demonstrate well the mood or attitude that each console was going for; especially the PS1 with how loud and overwhelming the music was. It felt like some powerful entity was awoken every time you turned it on.

Can you hear it bouncing when you see it? :D

Mine would have to either by the GC because I spent so many years playing on that system or else the Neo Geo Pocket Color because as a handheld it just sounded so happy and bouncy on startup, really gets you in the mood for some Sonic Pocket Adventure, great little handheld if ye never had the pleasure.

I love the GameCube one. It's just too iconic.