^ +1. AMD systems will run in dual-channel mode on 2 or 4 RAM sticks only.
What purpose will you use this PC for? If it's for pure gaming then 8GB is adequate and quite future-proof for a few years.
For the other two kits, I think Kingston's is quite decent. I have 2x2GB 1600MHz kit, set it at 7-8-7-21-1T timing and it works flawlessly.
Haven't tried Patriot's, though.