Well, I have played every New Super Mario Bros. except for the WiiU one. I think the Wii one is the best. It felt very atmospheric. NSMB2 felt a bit bland, but I got back to playing it and I'm quite enjoying the game. The first one on DS was cute, but I wasn't impressed cause I got to play it like ages after its release.
Welp, NSMBWii is my pick.