I liked New Super Mario Bros. U and its companion game New Super Luigi U (the whole package is optimal instead of one or the other). It might not look like it but it plays very well. If there's only one thing I would've liked, it's for Mario to get playable in Luigi U instead of just copying his physics and calling it a day.
I can't deny that New Super Mario Bros. (the DS one) is the most unique for its usage of things you don't normally see in other games, like bosses that aren't the Koopalings, or its unusual mode that prevents scrolling back. And of course, the minigames that aren't found in any other New Super Mario Bros. game.
I do think that New Super Mario Bros. Wii is due for a Deluxe version to address some of its shortcomings, such as penalising players for losing too many lives by not giving shimmering stars in the save.
Thank you for reading.