W7 will still be good for a few years before all official support ends
But you'll need to act fast becuz next year when Kaby Rape is rolled out you'll be only allowed to run W10
So if you need W7, you'll need to stick to older chipsets eg. Skyfall, Broadwell-E,.....
If you're buying desktop build then note that new W7p OEMs are drying up fast... get them before they're all gone
If however you're looking for laptops then there aren't many models to choose
Again, you'll have to act fast (probably within this month) before all existing models that come preloaded with W7 are all gone