Tough call. If I was on the market today, these 2 would be the ones I'd look and I don't see a clear winner, you will have to make decision based on your personal priority list.
Am currently using a 2011 Air and it has served me well, still on original battery, unbelievable
@1200 cycles. Love OSX interface smoothness, love that smooth zoom, love the large touchpad. I've used IBM eraser head in the past and don't care much about it. Windows' interface is not as smooth as OSX but is more "mature" to me. Some aspect of OSX, and I specifically hate FINDER, Windows explorer equivalent. Finder seems like hold over from 90s MacOS and never overhauled. Windows automatically remembers where you left your display windows and re-opened them in the same position next time, how hard is this? well OSX can't handle this simple aspect well. OTOH, OSX fits smoothly with your other Apple devices (the famed devilish Apple ecosystem), so my photos, reminder, calendar etc goes back&forth automatically between my phone and my laptop. OSX updates at least once-a-year, and after a few iterations, some of your Apps may not work anymore and you have to pay to update them. Windows, not so much, dang am still using a 1995 era Photoshop 6, I have no need to update it, it works just fine for my modest home use. MacBooks 2015 and later is having this butterfly keyboard problem, read it, watch it on utubes. So those are some of the majors on top of my head. I like to keep on Mac hardware and OSX but there are certainly annoyances. Is the dumb blonde who annoys you with dumb questions but she's blonde!
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