Have a 500GB SSD as my OS/boot drive, and two 1TB Drives in RAID0 (Striping for performance) as my data drive.

I backup my data offsite and onsite (to external SATA Mirrored Drives) using CrashPlan.

I don't back up the OS or any programs, because of the sheer space it requires. And I've been building and rebuilding systems for years.

As for Windows 10, I think it's fine. Improvements over 8.1, and haven't had any glitches at all since the upgrade (that I didn't already have, haha).