I really enjoyed No More Heroes, but wouldn't call it one of the 10 best third-party titles because there are so many rough edges and visible flaws. The problems are generally overcome by the interesting design and off-beat humor - but they remain very noticeable the entire time you play.
Aggregate rankings like these always produce some odd results, with lesser games that get played by many people ranking higher than polished games that only get played by a few. But seeing No More Heroes at number 4 is still a bit of a surprise.
Keeping my fingers crossed for personal favorites Rayman Origins, Rabbids Go Home, Dawn of Discovery, Tatsunoko vs Capcom, Little King's Story, and House of the Dead Overkill (among others)... but it's not looking good for the underdogs in that list.