We've put a lot of work into it and would like to think PopCoin could be one of the most interesting altcoins at least of this year 
Other than that, MaidSafeCoin is probably one of the most interesting crypto projects period, although the pace of development is somewhat of a concern. Lots of people don't realize that the core concept actually predates bitcoin, here's a talk of one of the developers gave at Google in 2008: https://www.youtube.com/watch?v=fLA77zxk-vA. Very interesting talk on it's own merits btw.
Other than that, MaidSafeCoin is probably one of the most interesting crypto projects period, although the pace of development is somewhat of a concern. Lots of people don't realize that the core concept actually predates bitcoin, here's a talk of one of the developers gave at Google in 2008: https://www.youtube.com/watch?v=fLA77zxk-vA. Very interesting talk on it's own merits btw.