What is your processor? Make sure that it supports 1.5v RAM cause if it doesn't then it might kill your processor. Buy any aesthetically pleasing RAM as speed doesn't matter except in 'certain' workloads. If you don't know what they are then you don't need them.
I have a closed case and don't care about aesthetics.
I clicked on this one as they are on deal down from £250
My partner dose a lot of graphic design projects and often has projects open that exceed 12GB of ram so the size is to allow her to work on multiple open projects.
The easiest way to figure out what to buy is to check the memory list supplied for your motherboard. The modules listed will have been tested by the board manufacturer themselves for compatibility.
Having said that, I find that RAM is RAM is RAM. Figure out the size you want and pick your brand. I personally like G.Skill and Crucial/Micron, but that's not to say other brands aren't good.
I second the suggestion that you buy only those exact models listed in the QVL for your exact mainboard. However, I wasn't aware of any problems with DDR3 compatibility.