I couldn't highlight any single aspect, probably couldn't narrow it down to half a dozen. I love everything about the sport, even the politics. Ok some of the fanpeople get on my nerves, but apart from that I love pretty much everything about it.
Lewis Hamilton has dampened my enthusiasm for F1. He's a bad influence for the sport, or maybe that's just his fans. Actually, it's his fans. Great driver, psychotic fans.
It's the technology for me. I love the constant battle of engineers to come up with something new, and then the panic from other teams to copy it, all to produce the fastest legal car, bending the rules so far as to barely resemble what they originally meant. That's something special in my opinion. And then you take these beasts from the hands of the engineers and aerodynamicists, and strap in a driver with the reactions of a fighter pilot, and send 24 of them hurtling around a track at breathtaking speeds, producing lap times within fractions of a second of each other.