I wasn't going to bother replying to this thread for a few reasons. Firstly, it's all been asked already...pretty much everyday. Secondly, maflynn and a couple of others with sense have given you the logical answer already. Thirdly, the vast majority that have replied have already given the OP what wanted to hear..."get 16 GB because why not?!"
Well, as maflynn has said, unless you need 16 GB it's totally pointless to have it. You won't see any extra speed in the computer's response times and loading applications won't be any quicker unless the applications being opened together cache over the nominal 8 GB you'd over wise have. Snappier reactions come with faster memory, not higher capacity.
What you need to ask yourself, or rather work out, is whether the applications you will use on a very regular basis will use over 8 GB worth of cached memory in total at any one time. You then need to ask yourself that, if it does come to over 8 GB, could you lower it by closing applications and running the most important by itself? The vast majority of us could max out our memory running applications like After Effects, Photoshop, Final Cut Pro etc. at the ams time but the vast majority of us would never need to run them all at the same time.
Perhaps, just maybe, IF you use applications such as those above in a professional capacity on a daily basis then you have good reason to claim the need for 16 GB of memory. However, the vast majority of people out there that claim they use/need such applications are either hobbyists or download them, stick them on their hard drives and then never use them...they just intended to.
