For online flowers, proflowers.com is definitely tops. I've used FTD, Kabloom, and a few others but as far as quality and customer service are concerned, Proflowers is way ahead of the others.
FTD and Teleflora contract local florists to deliver flowers. FTD (they have both online and local offerings) has VERY spotty quality with local florists and I can't really recommend them. Teleflora is MUCH more expensive but they use superior florists.
Your best bet for V-Day, if it's not too late, is proflowers.