Wanted to say that a bunch of games have demos on both 3DS and Wii U. If you are on the fence for many of these titles, perhaps give their demos a try first. I decided against Warioware games for the asking price, for instance. I was surprised so find so many demos, especially on 3DS, they definitely were much more common back in the day! Many videos did mention the existence of demos, but I wasn't quite aware how widespread they were.
Here's an Excel list to filter for demos:
List
A tough few final decisions for me ahead!