The SSD storage (i use a 240 GB Samsung EVO 850 for the system (it’s a good choice, if you planning to buy a SSD in the future) and the UE4 + marketplace project assets and other programs, like Substance Suit and Autodesk apps) is an essential thing for anything today (especially to a dev envirement), as i experienced, and you know; bigger is always better (CPU, GPU and much more RAM) in our case. 