Standard.

Nintendo entertainment system...straight to the game.

I think the misconception here stems from the fact that XBox is almost always in rest mode unless you go out of your way to do a full system shutdown.  As I am sure you know, hitting the off button actually puts it in standby and has no visual indication of what it is doing.

Yeah unlike older consoles in the year I've had my series I've seen the startup maybe 3 times.

Off the top of my head, my top 3:

1. PS1
2. Original XBox
3. PS2

PS1 and 2 sound so artificial but in a good way: they were machines/computers so of course they made machine/computer-generated sounds. Original XBox also sounded very artificial but also had the cool graphic of a green energy orb. The orb seemed to threaten to go nuclear before the XBox logo appeared as if sealing it away ready to use that sealed power to deliver some cutting-edge, heavy-duty gaming.

Gonna go through other start ups posted in this thread later, my interest is piqued.

That was a feature the Xbox One had as well... I have it turned off and such on all my consoles, including the PS5.
The startup is definitely there, loudly and proudly.

Less idle power usage then... Plus the Xbox had a habit of downloading the *entire* game in one hit rather than just the patch data, just better to do it manually... That and I don't have 1,000Mbps internet for another couple weeks.

Yep, the X1 had it too.  I went an entire year forgetting the start up screen even existed because of it, which is why I can see why the same misconception with the Series X/S.  A lot of people seem to mistaken it fornbeing the SSD not needing a start-up, since that is the buzz word of this generational leap.  But as you pointed out, that just isn't the case.

I think the PS2's will forever be my favorite.

My favorites are classic GB with its familiar jingle, the classic PS1 start-up sequence, and the GameCube start-up.

PS1: Probably the first I'd experienced. 9/10

PS2: Hated that sound effect. The pillars were cool though. 7.3/10

Dreamcast: Felt so "Crisp". I don't know how to describe it. 10/10

GameCube: Memorable but felt childish. 6/10

Xbox 360: Really cool. Never got old. 9.1/10

Xbox One: Can't even remember it and I played it today. 3.6/10

Xbox One X: I remember a motherboard or something. 4.5/10

PS3: Felt pretty classy with the violin sound. 8/10

Wii: *Shrug emoji* 5.$#-@/10

Switch: I think I saw it once or twice. Couldn't even describe it if it even exists. 2.004/10

PS5/PS4 Pro: can't remember those either but I feel like they exist. 3/10

PSP: Pretty cool, I guess. 7.33/10

DS: The sound gives me nostalgia but can't deny it was pretty basic. 5.5/10

3DS: Again, too basic. 4.1/10

Vita: Can't remember it. Not gonna YouTube it. 3/10 because it was probably cool.

Gameboy: I lied about the PS1. THIS is the first one I experienced! 6/10

That's all I've experienced up to this point.