I've played some of Super Mario 63. I'd say it's most likely the biggest and best 2D Super Mario Flash game on the Internet. I wouldn't say it's my favorite game on Newgrounds, but it's pretty well done.
I've also watched Balloon Head Fred. It was... very eddsworldy. I don't know how else to describe it. XD
Right now I'm playing Little Wheel. My favorite thing of the Top 5 today. I love the graphics, love the jazz, and the puzzles are simple but fun. I think it deserves its top spot among all these ridiculously high-scoring Flashes today.