Kindle? Or Nook?

I never wanted either one, but trying to read Margaret Thatcher's memoirs in bed led me to reconsider.  One volume easily weighs nine pounds--and there are three.

I haven't the least notion of the pros and cons of these gadgets.  Anyone?

I'm famous for buying gadgets I can't figure out how to use.  Speakerphone. mp-3 player, bluetooth.  So I need something idiotproof.