I am getting a new internet setup new modem,router,cables,etc... and am wondering should I get Cat6 or Cat7. What would be best? I get download speeds of 300mb/s and 50mb/s upload (according to TWC).
Depends on your budget. But if your only running short distances with little EMI interference cat 6 is all you need. However if your going to run cable through walls and your budget allows for it, you may as well get cat 7.
Even if you buy cat6 cable, most people can't terminate it to cat6 standards and have no way to test for cat6 standards. Solid copper -- NOT COPPER CLAD ALUMINUM (CCA) cat5e will work for just about anything.
A proper Cat6 termination is a royal pita. Cat5e is much simpler and unless you are looking at large amounts of electrical interference, Cat5e works plenty good enough not to worry about grounding issues.