I’d say for UE4 specifically SSD is not worth it. I got i7-7700 / 32Gb of DDR4 RAM and 7200rpm HDD… Engine source code build would take ~4+ hrs (maybe even 6 hrs). Just got 970 Pro 1Tb NVMe (PCie x4) and it’s been 2+hrs into building source. I am not even close to be done. So it does feel like money wasted.