I wouldn't say that as of today, the Switch has a much better 3rd party library than the Wii U. The Wii U had some solid 3rd party games, they just stopped support way sooner.
Switch WILL have a much better third party lineup in the end, but right now I would say its on par.
I mean Wii U:
2 COD
2 Assassin's Creed
2 Arkham games
Splinter Cell
Watch Dogs
Deus Ex
2 Darksiders games
Injustice
Tekken
Mass Effect 3
Again, I would say it is on par with Switch's CURRENT third party lineup.
1doesnotsimply







