I finally got rid of my sleep-on-the-sidewalk day one Wii this Xmas. Hadn't taken it out of it's under the bed box for 4ish years. Gave it free to a guy at work with 4 kids and little cash. His kids think Santa gave it to them. Feels good except when I think I should have kept WiiSports to play on my WiiU and gave those kids a different game to play. Wii Bowling will be missed at times...I will probably never get rid of my WiiU because of Rockband/Guitar Hero and the addiction to plastic instruments that can't be [reasonably cheaply] replaced because I have $1000's of items/songs that won't ever be available again.  [and a BIG thumbs up to Nintendo for quality construction on a item that was used for 1000's of hours and never even sneezed.] 

Yes, my GameCube and Wii are still hooked up to the TV :p

Depends. I can find Dreamcast, Wii, WiiU, NES and SNES for under 100€ each at an online reseller. Considering they want to make a profit off these consoles, they will probably pay you 50-70€ per console. Hardly anything to get excited about.

I kept all of them. I'm too lazy to sell them, so I store them away. I would just give them away if anyone wanted but no one wants old garbage. So they're gonna consume space and collect dust until I need space for something more important.

Currently collecting plenty of dust:

N64
GC
PS3
PS4(non Pro)
PSVita TV
About half a ton of old PC parts and cases, monitors and stuff.

When I said that, I was thinking about certain games that despite being 20 or even 30 years old have gained value for some reason. A lot of N64, Saturn and Dreamcast games are fairly hard to find and that reflects in the cost. Games like Conker's Bad Fur Day or Shenmue II or really any decent games that came out at the end of a console's life regularly cost more than the system they were released on, today. 

I saw a NES game called Bucky O' Hare. Never even heard of it, in a CEX near me being sold for £120. Just mental! 

I do now, when I was a kid however my mom would make me sell back my old consoles and games to raise money for the new ones. Which is why I no longer have my NES, SNES, and original Gameboy. I wised up around PS2 era lol.

i have a PS2 and an N64 tucked away in my closet. it would be too much work to sell them off and they arent worth much anyways.

I have a Xbox 360 and an Xbox One that i keep around just so i can have the controllers, also again i dont want to go through all the work of selling them off.

i sold off my Wii as soon as i got a Wii U, but i still have my Wii U even after owning a Switch for over half a year just so i can still play Wii U games if i ever feel like it. the Wii U is a funny thing, it has some good multiplayer games, and all my Wii save data is stuck on it, so i have to keep it around. no idea what I'll do when Nintendo eventually releases a Switch successor

as for handhelds, i like to keep two around at a time. i started with a GBA and then got a DS lite. i sold off my GBA when i got a DSi. then i sold off my DS lite when i got a 3DS. and then i sold off my DSi when i got a N3DS XL. now i am left with an original model 3DS and a N3DS XL. at some point in the future i may pick up a 2DS XL and then give my original 3DS away.

I have my NES, PSX (which broke so i bought another, even tho I play ps1 games on PS3), PS2(got 2 of em, in case one of them breaks), PS3 (got 2 of them too, in case one of them breaks, both of them FATs, a 80GBs Backwards SEMI compatibility, and a 60 Full Backwards compatibility), and a ps4, XBone, and a WiiU, Plus, 1 PSP and 2 Vitas (which I have because I tought I had lost the first one)

Nope, I sell my systems that I don't use anymore, first cause that's a bit of money I get back and second because I don't use them anymore so why keep them? They'll just gather up dust in some box so yeah.

I keep them. I´m not a huge collector by any means, but having the opportunity to play again old consoles is always a fun experience, specially when I have guests at home. Some of my younger  friends / relatives are always asking me to hook one or another console to the TV to try them.

I still have a project of arranging a gaming room when I finally get my own apartment later this year (something that,in my country, may take DECADES to get for someone with an average income like me) and I want to have my consoles for that.

Fortunately, all of them still work just fine, I never had to send any of them to repair or buy spare parts, although I do want to get another SNES and another Game Boy Color .