Had you asked me this question about 2009, I would have had a hard time choosing because there were a lot of really good parties. But you're not asking about 2009, you're asking about 2010.
The problem with 2010 is not that there weren't any parties. There were some parties, and they were almost all enjoyable. The year started with a fairly chill New Year's Eve party at my house. There were some sick dance parties (and some non-dance parties) at the household of Loud et al. There was the exclusive party on campus that I snuck into with some friends. They were all lovely parties, but none of them stands out as having "rocked my socks off."
I think my best answer to this question is that my favourite parties are the ones my roommates and I have whenever at least two of us happen to be in the kitchen/living room space at the same time. It's a new party every time. Last night it was a Trying-to-figure-out-how-to-do-the-worm Party, as well as a Balancing-pumpkins-on-our-heads Party (Not at the same time. That would be intense). Sometimes it's a Make-up-silly-dance-moves Party, others it's a Standing-on-the-furniture Party. It can be a Climbing-our-doorways Party, or a Rolling-around-on-our-spare-wheelie-chair Party, or a Making-random-beats-by-banging-on-things Party. We get up to shenanigans like nobody's business.