Should I stay with Windows or go with Mac? Thoughts appreciated?

So, I'm in the market for a new computer and am torn between continuing with a Windows system or taking the ethical plunge and getting a Mac. I've done some research and have narrowed it down to either a Lenovo Thinkpad x260 or a MacBook Air 13''.

The primary concerns for me are processing power as I need to run multiple programmes concurrently; and battery life. The two laptops listed above seem to have some of the best specs on the market.

If anyone has any experience with the two, your insight would be greatly appreciated. Alternately, if you have any other suggestions, I'm open to other options. My budget is about $1500.

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