This is a tricky one for me; I didn't own an Xbox One or a Vita, but I have played a lot of the former's games on Switch and PS5.
I did own a Wii U, and while it did have some excellent games, the droughts between them were terrible.

Xbox One has more good games, by a country mile, just by virtue of having good third party support. On the other hand, it lacks worthwhile exclusives, so the PS4 made it feel kind of redundant. Wii U justified its existence somewhat with the likes of Mario Kart 8, Splatoon, Tropical Freeze, etc, but if you weren't into Nintendo games or wanted a primary console it was a poor choice.

The Vita never held much interest for me, as I'd rather play on the TV.

Little bit off-topic: (I ask this as somebody searching for games to play...) Any games that come to mind for XBOne? Specifically, exclusive titles.

Responding to OP question: I only played Wii U...so I may be a little biased Lol. MK8D, Mario Maker, Splatoon, SSB4, Captain Toad, SM3DW, DS Virtual Console works beautifully with the second screen, Bayonetta 2,...need I keep going? Certainly Nintendo's worst line-up of any system they've ever produced, though far from weak.

I'd say PlayStation TV but unfortunately many of Vita's true exclusives and even non-exclusives with unique features were never supported due to Sony not finding workarounds on DualShock 3 or 4 for Vita's touch screen and rear touch pad. 

And yes, Wii U droughts were ungodly since very few have the money or interest to buy every Nintendo release and a lot of third-party games (many of them digital-only on Wii U) were either meh or shovelware. 

Xbox One is often very redundant in the face of its competition and PC, not to mention Series X/S. 

I like Wii U because of Super Mario 3D World, New Super Mario/Luigi Bros. U, Splatoon, Super Mario Maker, and Mario Kart 8.

But that's not enough for me to put it's library above Xbox One's.

In the end, Wii U. It did have Xenoblade Chronicles X and Hyrule Warriors. NES Remixes were also great and Wii U Gamepad has incredibly good D-pad. The 2D Mario games were rather mediocre, but still something that the others didn't come even close. However, the use of two screens was a pain for most of the time.

It seems that in the modern times wating for games plays a bigger part in owning a console than actually playing them. In retrospect, it's easier to judge how much fun you actually had playing the games instead of waiting for the messiah for the system to come.

Yeah the Wii U has a fair few excellent games now, but actually owning one during its time was constantly frustrating and consisted mostly of sitting around waiting through months of nothing for the next worthwhile release.

The fact that the Xbone had way, way more games makes me hypothesize that it would have been a better primary console. On the other hand, I can think of almost nothing on Xbox One that I'd consider worth playing that's not on PS4/Switch.

Really comes down to exclusives vs third party.

The Wii U and Vita both had great games, many of which ended up on the Switch, PS4, and PS5.

The Xbox One didn't really do anything that the PS4 didn't do better. Might as well not have existed.

I think all their best games were released on PC and other consoles later. Ori, Hellblade 2, Flight Simulator (this one I strongly advice playing on PC)

For Series X Valheim seems pretty good, my BF played the early access and I liked what I saw, I'm waiting for the proper release 

I would rather spend $300 bucks with some droughts and get 10 amazing games through 4 years than spend $500 in 2013 and, after a full generation, go to a Gamestop and just see a shelf of mediocrity.