Dunno. They're all pretty close.
* I might say "food" because I love to eat. I consider myself an aficionado of salsas, onion dips, pizzas and cheeses... but there are times I'm closer to sewer than connoisseur.
* I might say "sex" but like they say: sex is like oxygen, when you've got it, it's no big deal... And when you're not, you're freakin dyin' (ahh, the bad old days.).
* I might say "sleep." I do tend to stay up late writing, playing (take that how you will...). Sometimes I get up after a three-hour nap and go to work, other times are more luxuriant. I've gone for three days without sleep just for grins --and I go into a freakin' coma when I'm done. Just ain't that young anymore, dang it. Yet for all the recreational sleep-deprivation I've endured, I can't tell you what a pleasure it is wake up at the crack of lunch. I dunno, some of you probably already know...
* But I voted "adrenaline." There's something about the rush. Especially since my wife seems to be a genetically DRD2/DRD4-positive thrill-seeker. It doesn't hurt that it becomes a type of foreplay, too. We're intelligent about it -- there's enough daily risk just driving down to pick up a gallon of milk -- so we set up redundant anchors, etc., and really put the "calculated" into the "risk," but there's always that chance Murphy will show up... and that, I suppose, is what makes it exciting...