Since I have a year to make the decision for free, I'm sticking with Windows 7 until the Verdict is in. Feel free to be part of the verdict :-)
Do you have unmetered/unlimited broadband? If not, you might consider giving Win10 a miss right now. Hubby (an IT technical architect) says you cannot elect to NOT update on their schedule (or put off updating at all), and the minute your computer begins the updates, you begin uploading the updates peer-to-peer as well - doubling your traffic. It is claimed it won't do this IF it detects the computer is on a metered connection, but since when do we trust Microsloth to get something like that right?
I suspect this will be one of their major problems, but not their only problem. We're giving it a miss for our three computers for now, and will not be "upgrading" my mother's or mother-in-law's computers either :/