I like both W7 and W10.
If you make an image of your W7 install with something like EaseUS ToDo Backup (free, and what I did.) then upgrade the current W7 to W10.
Play with W10 (I'd recommend a clean install once it's been activated after the upgrade.) and if you don't like it re-image W7 back to the same state it was in before you tried W10.
If you want, and have yet to accept the upgrade prompt, I'd image the drive first to avoid the extra content the W10 upgrade will added to your system. (Downloaded files.)
If you are concerned with the whole "spyware" thing with W10 use O&Oshutup10 (or other) and lock your rig down as you see fit. (Lots of options.) Though I understand some folks reluctance to move to W10 for this reason, I personally am beyond giving a [censored]. (O&Oshutup10) It's a personal decision you'll have to make for yourself.