The most exciting moments of bowling or batting can be considered to consist of opposition wickets and boundries. For me, it's far more important and thus exciting to to see a wicket fall (like today against Kallis, or Ponting v Flintoff in '05) then to see a well executed cover drive. As a result, I'm very much a bowling man.
The tension and excitement that I experienced this evening watching Flintoff continually beat Kallis, but Kalls looking like he'd somehow escape, until Freddie removed his off stump, gets the adrenaline and heart-rate going a lot faster than any batsman's innings could. And when I think back to my favourite cricketing memories, it's Caddick's 4 in an over at Headingley, Harmison's 7-12, Jones removing off poles at will at Trent Bride, Clarke falling to Harmison so late in the day at Edgebaston... That's what I love and cherish.
It might also be something to do with the fact that you can never relax when watching England bat...