Either case should be good cooling. I prefer the bottom PSU mounting of the Antec since your extra power cables can lay on the bottom out of the way instead of needing tied up somewhere and dangling down over your components blocking airflow.
I agree, that is nice. For top mounted PSUs, I usually tie them up real good and tie them to the top of the chasis or tuck them in empty spaces under the optical drive. It doesn't have to block much airflow. Though, it's not as much of a problem with modular PSUs