A:Answer I don't want to sound like a smartypants, but more space is always better, but the hard drive doesn't really affect your performance. The difference between this one and the BB5203EA model is that this one has a 1080 ti (best graphics card on the market right now), and that one has a 1080 (not the ti). It is also using a ryzen 1800x processor, which has a little less power than intel i7 7700k (kaby lake). I don't actually have any personal experience with Ryzen, as it's VERY new. I know it didn't quite meet expectations in some tests, so keep that in mind when considering. However, Kaby Lake has had issues with overheating if overclocked, so if you want to get more than 4.2ghz, you might have an issue. I personally haven't even had the need to overclock mine, and I can run everything with max settings fine. I play TERA quite a lot and get 80 fps normally. Other games I get a lot more.
So in my opinion, get this one. Or wait until intel drops the i9, and get something with that. Ryzen is just too new for me to be able to recommend.
Hope that helps!