Yup.  Today’s consoles would be lacking many features had the OG Xbox not released.  Not to mention a few of today’s biggest franchises and leaders in their respected genres.

Flawed thread gets no vote from me.

The PS2 because it has many of my favorite games.

Entering only 1 modern console into the poll is the definition of bias no matter how you look at it.  Here's your OP:

"Pick which console you were most fond of at the time that you owned it. (not which one you'd rather play today, because that would bias this to the most recent ones)"

Contradiction #1:  You include PS4, Sony's most recent offering in the poll.  Proof of contradiction:

One of the PS4 voters even declares "There is no other system I'd rather be playing today than Ps4.", which specifically contradicts the claimed intention of the OP.

Contradiction #2:  You intentionally leave Switch out of the poll.  Citing:

"Switch is too new, it would just be recency bias."

Contradiction #3:  You state that its okay to include PS4, because 4 1/2 years is not recency biases.  Yet, you intentionally also leave Xbox One out of the poll, even though it is also 4 1/2 years old.  Citing:

"with xone being somewhat irrelevant this gen I excluded it since I couldnt fit it. and wasnt like to get more votes than the ps4"

So Nintendo gamers who are enamored with the Switch can't vote for it, because you have decided that it is too recent.  Meanwhile, Xbox gamers who do like the Xbox One can't vote for it, because you have decided that its 37 million sales are irrelevant.  All the while, you do leave a place for current PS4 owners to be the only gamers this gen who can vote for their console.  How many spots on the poll can be filled in is not the issue.  That you chose to enter in an option for Sony's most recent offering without allowing any votes for its competition is confirmation bias, plain and simple.

If backwards compatibility is a factor then an original 60GB PS3 is hard to argue against, well the PAL model was lacking in PS2 compatibility but is still enough to lift it above the PS2, I think. It's a close call, complete PS1 with partial PS2 and full PS3 support versus complete PS1 and PS2 support.

If BC (or even FC) is not included then it's much harder for me. Probably the PS1 but PS2 is very close.

Wii U, because you also get Wii backwards compatibility so I can play both of my favorite games of all time (Blade and Blade X), Bayo 1 and 2, the best Smash Bros, remaster of 2 Zelda games + BOTW, the Galaxy games, the Prime trilogy, Wonderful 101, Fatal Frame V, Tokyo Mirage Sessions, The Last Story, Skyward Sword, Fire Emblem Radiant Dawn, Donkey Kong Country Returns/Tropical Freeze, Mario 3D World, and Mario Maker to name some.