I'd say the Antec power supply marginaly.

Firstly both have (or claim) silent fans.

Secondly both have ratings of 80% on power efficiency.

Thirdly both are certified for SLI and have a 5 year warranty.

However the Antec power supply wins out because it is modular.

This means there are sockets where you plug in cables only when you need them. This reduces clutter i.e improves asthetics if you are bothered and also improves airflow because of the lack of obstruction.

Answer:
I’ve the 750W version of the Corsair psu. It works great, and I would suggest it over the Antec because it only uses 1 12V rail instead of three.
Answer:
Antec are a good brand (I have the Antec 900 case - a true beast), but of the two I'd recommend the Corsair - I think you'll find the cabling easier to manage.
Answer:
I am ordering the 750W version of the Corsair. That's a pretty good line of PSUs, I would advocate that.