Here is a website Nintendo just launched which shows you overall playtime for 3DS & Wii U, as well as your top 3 most played on both systems: https://my-nintendo-3ds-wiiu-memories.nintendo.com/en-US/index.html#top

For me:

3DS

3348 hours overall

Total titles played is 98

1. ACNL - 325 hours (ACNH blows this out of the water for me)

2. Pokemon Y - 316 hours

3. Pokemon Sun - 305 hours

Wii U

1800 hours overall

Total titles played is 61

1. Smash Wii U - 385 hours (SSBU blows this out of the water as well)

2. BOTW - 299 hours (Daily Log actually says 300 even)

3. Mario Kart 8 - 220 hours (I have 140 in MK8DX, but I could see DX surpassing it)

Seems like roughly half of my playtime comes from just these three, not surprisingly!

I know it is kind of a pointless feature because 3DS & Wii U do a good job tracking playtime, but this is still nice to have. Would've been a pain to add up the total playtime anyways.

Bonus:

My most played on Switch are ACNH (725 hours), SSBU (545 hours) & MK8DX (140 hours). Fully expect ACNH to reach 1,000 one day and I think SSBU could reach 700. As mentioned, I think MK8DX can surpass MK8. I don't think I have any other titles exceed 100 hours, but I do have a lot in the 70 range. I don't play Pokemon as much as I did.

What are your stats and would you like to share your Switch stats?

I would love to know how did I do on Wii U as a whole, buuuut... I lost access to my NNID long ago. I'm screwed.

My top game should be Xenoblade Chronicles X, and any less than 800 hours would be false. I don't think I really played any other title (besides FIFA 13) for more than 100 hours.

I know for a fact that my NNID is connected to my newest 2DS XL, but for whatever reason it says no 3DS gameplay records for this NNID are available. Really weird.

Either way, with my old 3DS that I don't use anymore and never connected to any Nintendo account and my current one I must have over 10 games with over 100 hours, especially since I've replayed some of them over and over again.

I’m actually a hardcore gamer, but for Wii U it was Wii fit U. For 3ds it was Brain Age: concentration training.

3DS is a surprisingly low 239 hours with my most played titles being Pokemon Moon, Xenoblade Chronicles, and Ocarina of Time

My Wii U stats are pathetic (6 hours) but that's honestly because A) I got the Wii U in 2019 to help a friend buy his own Switch and B) pretty much every game I wanted for the Wii U are on Switch. Aside from Xenoblade Chronicles X which I've been meaning to play but just can never find the time. I guess this is a hint to me that I need to play my Wii U or else I pretty much wasted 150 bucks

Wasn't quite the biggest Wii U player as you can see. 3DS is a bit higher (and more evenly distributed) and that's a number I could easily see continuing to rise as there are a couple of games I've been meaning to play or revisit.

Also I may and may not have played a game or two emulated at some point, which would of course not show up here (if of course that had been the case)

Fun! I’ve already seen something that surprised me on mine, but I’m on mobile so I’ll post the screenshot later if I don’t forget.

My Nintendo 3DS Stats:
Total Play Time - 1,202 Hours
Total Titles Played - 48
Favorite Genre - RPG (by far. XD)

My Top 3 Games:
1. Fire Emblem Fates - 159 Hours
2. Xenoblade Chronicles 3D - 152 Hours
3. Fire Emblem Awakening - 117 Hours
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My Wii U Stats:
Total Play Time - 1,225 Hours
Total Titles Played - 36
Favorite Genre - Action

My Top 3 Games:
1. NBA 2K13 - 245 Hours
2. Hyrule Warriors - 157 Hours
3. Xenoblade Chronicles X - 106 Hours
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Wow, I put a lot more time into the Wii U than I thought. I was such a basketball nerd back then and I couldn't afford any other consoles while I was in high school.

Yeah, 3DS stats are completely all over the place. For some reason it only kept track of the short period of time I had a 2DS and only played Pokémon X, Professor Layton and the KH DDD demo.

Wii U is fine I think. I was really into MK8 and Splatoon and I completed like 3 100% playthroughs of Wind Waker HD.

I can totally see why Xeno X is my most memorable Wii U game. While not in my top 3 of most played games (although it has to be very close to Wind Waker's 90 hours) it's certainly the one that hooked me the most. Exploring Mira was one of the best open world journeys I've ever experienced. Not only because of the fantastic world design, beatiful visuals and the fact that there's always something new to do or see... But because of the sense of progression.

When you are on foot, you can still go to many places at first glance would seem impossible to reach. You can climb many mountains and jump really far away. Then you get your Skell and you can go to even more places. And then you can fucking fly on it... And the world is yours. I never felt anything like this game before, not even with Breath of the Wild. 

The Wii U was one of my favourite consoles ever. It had so many great games, some of them with unique gameplay that made them be better for it. It also made playing a home console a lot more comfortable thanks to the off-tv feature. And thanks to that, it also had  the most convinient and easy to use internet browser on a console ever. I have probably put in thousands of hours just on Youtube, web browsing and other streaming services.