About SSHD; get the biggest one your cash can afford, since it will last longer than smaller versions. Probably like 50+ years, without breaking a sweat.
Goog "SSHD life expectancy" to get the full picture on what I'm talking about

Also, just an FYI, a 2.5" laptop size SSHD of 128GB retails for about $5K (WHich is more than most full computers)