I like the wiiU from a hardware perspective more but if I had to choose one, I'd go with the 3ds.
The reason is because of a large lack of games. The 3ds always had a good mix of first party and third party games to keep me active while the wiiU was like... I sure hope you like waiting for Nintendo games cause that's all you are gonna get. Waiting and Nintendo games... Like I obviously get Nintendo platforms mainly for Nintendo games but the waiting was nuts! Luckily I had other platforms to keep me going in between the wiiU droughts.
Plus I do like being able to see tits in 3d.
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850