Well the Wii U had decent 3rd party support around launch, but that dropped off a cliff quickly. Meanwhile Switch's 3rd party support started off really strong, and continues to get better as time goes on.
Wii U didn't get a Mario game in the vein of Galaxy. It didn't get a real Zelda until after it was dead. Switch got both in the first year.
Two years into the Wii U's life cycle, I owned about 9-10 games for the system. Meanwhile I own 24 physical Switch games, and countless indies.