I liked Windows 7 and was reluctant to upgrade to 8.1. Once I did though, I was pleasantly surprised. Luv the quick bootup time.
You're one of the lucky ones. I will guess you'll be even happier with Win10. It's got all the good things about 8.1, and adds back some of the good things about 7 that were originally lost when they went to 8.
People who liked 8.1 are generally VERY happy with Win10.