I'm not being self-righteous! And if I am to your mind, you don't then think it's "self-righteous" to dismiss someone's point as 'really now?' Come on.
If I had to list some, it'd be
1. Super Meat Boy
2. VVVVVV
3. Rayman Origins
4. Wario: Shake It (this one will probably be controversial to some; I'd say the approach to challenges and visual quality slightly put it over NSMB titles)
5. And Yet It Moves
6. Fez
Actually I think Wario and Rayman are the least controversal choices (though I disagree on both!) despite VVVVVVV, which I haven't played and can't comment on.
Super Meat Boy is super floaty and challenging in a total unimaginative way. It's just "Many ways to die" and its level design is can only really reach this one goal (being difficult).
And Yet It Moves and Fez barely qualify as platformers (if judged as platformers, both miserably fail for their jumping physics), they definitely are more of puzzle games than platformers, so I don't think they really are comparable.
As for Rayman Legends and Wario - which I thoroughly enjoyed especially for their higher degree of diffculty and their higher speed than the NSMB games - here I think several points still knock them down below NSMB on a purely gameplay-oriented comparison (of course, their style is infinitly better and I can accept that one could value that higher than me, I always solely focus von gameplay and level design when comparing platformers, so keep that in mind):
Starting with Wario:
- The level design is too much depended on the additional missions. Play the game without completing the missions and it feels stale - and also laughably easy.
- the fast-paced areas are sometimes (not too often, but still) unfair in that you can decide on what is being shown on-screen, whether to jump or not to jumo. You have to remember the level and can't without gambling complete every mission on first try.
As for Rayman:
- the controls are less spot-on than for Mario, they are a wee bit slugish
- the levels don't adapt to different playstyles too well. You can feel this especially on multiplayer where the level design often times falls flat a bit
- the levels are often not too well timed for the games time attack missions - which leads to totally unsatisfyingly easy times to beat
The big advantage the NSMB series has over all the other platformers I've played this gen (and I usually play all of them, even the download ones, despite hating downloads) is the highly adaptive level design, best demonstrated by the levels in NSMB Wii and this game's multiplayer aspect. This game plays perfectly well wether you play solo, two player, three player or four player. You can rush through the levels using the highly dynamic platforming system or look for all the secrets for additional platforming challenges. It's less easily seen in NSMB2, but if you play the coin rush mode you really learn to adore the flexible level design that adapts perfectly to speed based, exploration based, or pure platforming oriented play.
There indeed is one thing all the NSMB games are lacking regarding gameplay and that's challenge. But other than that there's little room for improvement. As I said this is strictly speaking of gameplay, music, graphical style and visual variety are not being taken into consideration here. Regarding 2D platformers I'd still rank the NSMB series absolutely at the top of this generation. By the way if it's challenge you're looking for in a platformer and if you like Mario's base gameplay, maybe take a look at Yoshi's Island DS. It has awful music and starts slow, but it gets really challenging

.