I've only heard that 7 won't work with Intel's newest Skylake cpu's. I haven't heard that about 8.1. I've also noticed a stupid Windows Store issue in 10 that didn't exist in 8 or 8.1. If you reinstall your o.s. provided you store your settings in OneDrive 8 and 8.1 would automatically reinstall all the store (modern apps/games), you had installed. 10 doesn't do that, so you have to waste time going through your list, which could be hundreds as, if you have/had a windows phone, it's stuff is in the list, too and then remember what you had and click each to reinstall. HUGE STUPID 10 HEADACHE.