Buying your own cable/router/gateway is the best choice. It's cheaper in the long run and you can guarantee you're getting a decent product. In my experience, Xfinity's rental equipment does its job, but it's definitely not great. Besides, after 9-10 months you'll have paid for the cost of a decent cable+router or gateway device had you bought your own. If you have your own cable/router/gateway, you get to keep yours if your Internet Service Provider changes. Make sure to read the manual!