I'm a huge fan of the genre and so the best HR tends to be the one I've just finished (unless it bombed, which does happen from time to time!)
However my best HR of 2010 was 'Love in the Afternoon' by Lisa Kleypas.
I started reading it because the heroine, Beatrix, loves animals (and I'm a vet, so I was curious as to how this was handled) and I became enchanted by the sensitive way that Ms Kleypas used Beatrix's patience to help Christopher, who was suffering from the Crimean equivalent of shell-shock.
What about you? Any good recommends from 2010?