Questions about RAM and help choosing the right one

So I guess I'll start with the question. When deciding between RAM, what is better, higher frequency or lower timings?

I'm building a new system and I'm having trouble choosing between some OCZ DDR3-1333 PC3-10666 CL 7-7-7-20, OCZ DDR3-1600 PC3-12800 CL 9-9-9-24 or Corsair DDR3-1600 PC3-12800 CL 7-7-7-20. Now the two OCZ kits are about the same price, but the Corsair kits is more than twice as much. Is the Dominator stuff that much better? I should clarify that this will be going into an AM3 system. Also, when RAM says it's designed for i7 or i5 systems, does that mean it won't work with AMD or will work poorly? Because most of the high end RAM kits say they are for intel. I don't want to get something that won't work with my build. Also, if I've missed out on looking at some other good memory, please let me know. Thanks.