Hi, that will depend on your needs too.https://www.xfinity.com/support/devices this website will help you to check which device will work with your internet speed plan, you can sort devices by brand and speed tier. All of our gateways have parental control settings

https://assets.xfinity.com/assets/dotcom/projects/cix-4997_compatible-devices/CIX-4997_Full-List-of-Compatible-Devices.pdf this link also contains a full list of the compatible devices with Xfinity

If you do not require much speed myabe the best option for you is the SBG10, https://shop.surfboard.com/wi-fi-cable-modems/?sort=pricedesc 

But take a look and made the best decision for your needs!

I’d look at something that’s docsis 3.1 compatible. Xfinity has been pushing more for lower speed tiers needing docsis 3.1 to work. And I see that getting worse as they push for faster speeds and docsis 4.0. 

More along the lines of the G34/G36