If you're like me, and leave your computer on 24/7, then go for the Enermax. Antec's supply didn't hold up in mine running 24/7 and it's flakiness eventually damaged my motherboard. I went with an Enermax, and between that and the rebuild after the motherboard fiasco, my computer appears to be more stable, with fewer lock-ups.
Incidentally, my 300 watt Antec was in a barely 14 month old AMD Athlon Slot A 700 setup with excellent ventilation. Now my rig is a Socket A 1 Gig Athlon in the same case.