I'll agree with old-school Chad Hunt (before the long hair), and DannyD is awesome. Since I'm mostly gay I of course watch his Matt Hughes incarnation, but he has some hot straight vids as DannyD as well. For the why in each case: because their cocks are HUGE and especially with Danny so are the loads!
An all time favorite to watch is Rafael Carreras. Huge cock but also so sensual, he is really into any and all sex he has it seems and that makes him hot to watch.
Just lately I've been on a Dominic Santos kick - he seems like a normal guy who is just insanely hot, can suck his own dick, and loves both bottoming and topping.
Luan Mastro is amazing for me to watch just for the big dick and domineering attitude he often displays.
There's a Brett Bradley - Armond Rizzo scene that is extremely hot. Armond Rizzo is the best bottom working today imho.