Which RAM will be better? Cheers! Which RAM will be better for my iMac 27" mid 2010 with i7 2.93GHz and MacOS 10.9.5:

this, this or ADATA DDR3 SO-DIMM 8GB 1333? Also I have saw Kignston KVR1333D3S9/8G but according to it data-sheet it works with 677MHz instead of 1333MHz (as I understood my iMac supports up to 32GB 1333 MHz PC3-10600 DDR3 SO-DIMMs with 204-pin). Which one is better?

Actually I want to get 20GB of RAM - 8GBx2 new plates + 2GBx2 of stock memory.
Anything that matches the required spec should work. I've used Corsair and Kingston RAM without issue, and branding seems to be a somewhat personal preference. Most of the time, I get my Mac RAM here though and have never had issue.

Your aspiration for 20GB will be fine in your poroposed config.