Surprised there are no other answers, though I'm late in participating!
I love tennis which I've played and watched for years. I played for my school and later for a local tennis club. I especially love watching Wimbledon but then I would, wouldn't I?
Badminton is also one I enjoy playing.
The ones I watch are MOTO GP (I love motorbikes) and British & World Superbikes championships. I'm a biker and the thrill of watching such high-speed racing is 'edge of the chair' stuff!