I think I enjoy most races, even if, in retrospect, they're not particularly stunning, but I've tried to narrow it down for this year:
Bahrain - the Mercedes dual, just taking off after the Safety Car came in, plus the other team-mate duals.
Monaco - I know that overtaking is limited, but Bianchi did manage at least one (that I remember), and of course he and Marussia got their first points, so from a feel good perspective, I enjoyed the race.
Austria - too young to have seen any races here before, but I really enjoyed it, one of my favourite tracks now. Lewis' first lap was extremely enjoyable, as was the fact Williams were a threat.
Great Britain - as has already been said, the Alonso/Vettel scrap - I really enjoyed watching them race each other hard, and it was very amusing to hear them on the radio.
Germany - enjoyed watching Lewis come back through the field, and Daniel Riccardo too.
Hungary - a lot of fun, especially with the rain at the start.
Singapore - JEV's overtakes were a highlight for me.
Japan - obviously before Jules' crash. Vettel and Ricciardo's overtakes, Lewis's speed after he overtook Nico, plus the overtake and the preamble to that.
Hoping my list will be as long next year