Well the current mainstream AMD mobile unit, the 4700U, slaughters the i5-6500, and the entry level 4300U exceeds it, so no matter which 4000 series CPU you choose in a laptop it will exceed what you have now. I would suggest the 4700U or higher because that's what you'll find in the current $750 segment of the market, good all around with no major drawbacks laptops, plus as you move up the stack the graphics improves as well.
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