1600mhz definitely. Agree the timings are too slow on the 2000mhz, and you'll never need that much bus speed. The lower timings (if you can tell any difference at all) would be more desirable.
CAS 9 on 2000 isn't slow, and CAS disparity {7-8-7-20} is worst.
I'd need to know (2) things - 1. What MOBO {verify either RAM is compatible}, 2. Both RAM part-number and or links. Also, 2000 MHz RAM only works properly for extreme OC'ing ~ 4+GHz.
I don't know since the price diff is small and your mobo support 2200 mem speed,. But unless you go for heavy overclocking (like using nitrogen or dried-ice pipe) you should stay fine with 1600 low timings.
2000MHz RAM's are really for the high end enthusiasts who overclock for fun. That is why i recommended the lower timing 1600MHz RAM's. And 1600's RAM's are no slouch in overclocking as well.
The 2000 MHz memory module(s) can be downclocked and made to run at 1600 MHz speeds at much more even timings such as 8-8-8-24 or even 7-7-7-21.. So, for a 10$ difference, i'll say they are worth it..
I would ONLY use the GA-X58A-UD3R "IF" I were building a "Hackintosh" {hacked/homebuilt Apple PC running off Intel MOBO}, otherwise I strongly recommend the ASUS P6X58D-E paired with Corsair Dominator 1600 MHz part-number TR3X6G1600C8D 3x2GB.