Super monkeyball banana blitz! A few tricky ones at the end kept me going for ages!
I STILL haven't beaten that... you know, the "hardest-stage-in-Monkey-Ball-history" stage? xD
It's like difficulty 20/10. xD
It's that difficult. That's the only stage I have left still after so long. I have really good scores in the game overall (see: EliteScores).
I love SMBBB.
But for me personally, I still haven't "beaten" SRZG entirely, so I'll have to say Rayman Raving Rabbids 2.