I'd have to say Super Mario (ᴾˡᵃʸˢᵗᵃᵗᶦᵒⁿ) Allstars (ᴮᵃᵗᵗˡᵉ ᴿᵒʸᵃˡᵉ)
Specifically the Super Mario All-Stars + Super Mario World version, with the updated version of Luigi since I liked that he wasn't just a palette swap mario in that one. One of my favorite games ever. And in my opinion the best way to experience those games in general.