Rockdpm indicated two excellent choices - I am very partial to the GSkill RAM...I use it in all my builds.
One thing to keep in mind - it is always best to buy a "kit" containing all the RAM you are installing - as they will all be from the same production run.
I see all too often where RAM is added after the fact - either mismatched RAM (different Manufacturer and/or Model) or the RAM is from a different production run. The first mismatch will create issues 99% of the time, the second 50% of the time.
Since RAM is inexpensive as compared to other components - always buy the kit. If you are upgrading, best case scenario for the old RAM is to repurpose it in a machine as a complete kit....don't just add extra sticks.
So your saying just go ahead and buy a full 16GB kit whether it be 4x4GB's or 2x8GB?