3 I definitely spent more time playing growing up, so I occasionally lean slightly in that direction, but World added so much neat detail and polish and a level of flexibility that still hasn't really been improved upon in 2D Mario platformers since
3 felt landscape changing at the end of a console’s life which is very impressive even now. SMW builds off it, and you don’t get it without 3, but also I’ve always felt even as a kid that it had less variety, both in environments and power ups, which always has me gravitate back to 3, especially once All Stars was out.
like yeah there's secrets to find in 3 but you don't have that same feeling of seeing a warp pipe on the map and going "hm, i wonder what i have to do to open the path to that" and then trying as many obscure side-paths in nearby levels as you can find to try and figure out where the secret level exit is
also being able to queue up a backup powerup that you could swap between was very cool and i don't think any mario game since has done that, to my knowledge
I did this poll once, and was sorely disappointed.