I never played the Saturn, but I have a love/hate relationship with the WiiU.
Currently I have it kicking around because it's a nice GC emulation machine and can play Wii and VC games all in one. The Pro controller is also great and I still have 2 of them which I use on it, my computer, and my new Switch via an adapter.
The WiiU's library itself? Ughhhhh I guess it's great if you really like their 2.5 Platformers. It lacks a lot of the variety that the Wii had. The Wii had stuff like Mario Galaxy, Prime 3, Zelda, and bunch of unique 3rd party efforts as well.
The WiiU has only 3 games that I felt made purchasing it actually worth it. Bayonetta 2, Xenoblade Chronicles X, and Breath of the Wild, and of course BotW was a Switch game too. There was no Metroid game, BotW took it's whole short lifespan to release, so I had to get that fix with HD remasters of WW and TP, and the new Starfox game I waited forever for sucked.
In terms of it's own library, it's severely lacking.