If your 2010 is a V6, then moving to a newer model won't affect your towing ability very much. 2010 V6 was up to 5500 lbs with tow package, while 2011+ is up to 5000 with tow package. But if your 2010 is a V8 with the factory tow package, I recommend you keep it as a dedicated tow vehicle, and find another fuel efficient vehicle (if you need to) as your daily driver. V8 with tow package is a great tow vehicle, up to 7300 lbs.
As far as factory or aftermarket, I'd always recommend factory if you can, especially if it's a matter of axle gearing or alternate radiators. If the components to be updated is only for trailer light wiring, additional trans cooling, or even trailer brake wiring, that not a big deal. Likewise for a class 3 receiver. Aftermarket is fine.