I prefer Windows 7, simply because Microsoft failed on Windows 8. No offense, but Windows 8 is more suited to tablet usage vs. Windows 7. Although Windows 8 is faster (generally), a Windows 7 computer, with a decent amount of RAM and processor can work as well as a Windows 8. Windows 7 is a good choice as to familiarity and general usage for longtime Windows users but also costs a bit more (roughly 20 dollars+). Apple can make computers, but is a waste of money if you want a performance computer, especially for gaming or making videos etc. Although Windows 8 "has the same desktop as Windows 7", it's a stripped down version, only allowing some features to be used, primarily pushing users to adapt to the new Metro interface.
More to the point, it all comes down to your opinion on OS, it doesn't matter at all which ever you choose. Just remember to get a good computer for your pricing range, and as long as you choose a good computer, maintain it, it will work. Take note that most software for Windows 8 is not updated yet, and will take some time for normal software and programs to be set up for Windows 8. (Some companies have decided not to update to Windows 8, but most programs will)
--- Advice from a computer and tech nerd
yit63