My primaries have been
GameCube (GBA on the side)
Wii (DS on the side)
3DS (Wii U on the side)
Switch (kind of coexists with the PS4, but more of a secondary function for part of 2019 and especially late 2020 to the present)
PS4 (Vita and PS3 on the side)

Judging by the years most people started, there are two likely conclusions. Most of you are 5-15 years older than me, or you were gaming since preschool (even if only a few hours a year).

Consoles: NES -> SNES -> N64 -> Gamecube -> PS3 -> PS4
Handhelds: Gameboy -> GBA -> N-Gage -> PSP -> PS Vita -> Switch -> Steam Deck

Since 1998: PC

I had a bunch of other consoles and handhelds over the years, but I didn't use them too much so I just counted devices that I really got the most out of. And yes, I really did use the N-Gage a whole lot. That thing was fantastic for its time.
As for the Steam Deck: I only have it for 4 weeks or something, but it already became my main gaming device. I'm absolutely in love with that thing. Although it is debatable if you want to count it as a handheld, a PC or both. I'd go for the latter.

Started with Commodore 64 and Amiga then following Commodore's demise my gaming history has since consisted of a long line of gaming PC's, stretching over the decades and while not always being day one launch purchases I have owned the main consoles of each gen since then from Nintendo, Sega, Sony and Xbox, along with Nintendo and Sony handhelds.

MSX
PC
PS1 (N64, Pentium 90)
PS2 (XBox, GameCube, Dreamcast, Pentium 2 266)
PS3 (XBox 360, Wii, i7 940 desktop)
PS4 (WiiU, Switch, i7 gaming laptop)
PS5 (Series X, i7 8750H gaming laptop)

I just got the Series X today, got to set it up now :)

NES>Genesis>N64>PS2>360>PS4

PS2 may have been primary but XBOX and GCN got a lot of play time as well. PS3 became primary halfway through 7th gen.

I'm the one who voted 2005-2009. Not sure which year exactly.
Very boring list incoming:

Wii/DS -> Wii/3DS -> Switch

Almost never actually used the Gamecube, played it's games on the Wii.

Been gaming basically since I was able to hold a Intellivision controller so I say ~ mid 80's.

1)Intellivision

2)NES

3)SNES

4)PS

5)PS2

6)PS3

6)PS4

I don't currently own any current generation console

I been gaming on PC since 1994 and spent way way way more time gaming on PC then all consoles I played combined.  Most my life it was JRPG on consoles and PC for everything else.

My list is very similar.  I started gaming in 1982 and have owned every major console and handheld except the PS3 and Vita (if that's a major).  I don't have a PS5 yet, but I will get one in a couple years.  

1. 2600
2. Master system
3. Genesis
4. Saturn / PS1
5. Dreamcast / Xbox (This was my least played generation)
6. Wii / 360 (Wii early in the gen, 360 later)
7. XBO (PS4 Pro later in the gen, but the Xbone was my primary for most of it)
8. Series X

Atari
Master System
Genesis
Super Nintendo
Saturn
N64
PS1
GC
PS2
GBA
PSP
PS3
Wii
DS
X360
PSVita
3DS
PS4

WiiU
PC