Wow, you got one more year out of yours! I own a 2010 too that I never sold or traded in. It doesn't hold a charge anymore but the keyboard works perfectly. If I could combine my 2010 and the 2015 I'd have a perfectly functioning laptop!
The Air is such a good value. If you're stuck in the Apple ecosystem I don't think there's a better choice unless you're a hardcore gamer or video editor. Did you spring for the 8 Core/16gb memory? Kind of scary that you're having an issue with Text Edit.
Thanks @creatr. Good to hear from you! Take care of yourself.