Netgear CM1000 or Arris SB8200 for docsis 3.1 gigablast?

They have the same broadcom chip but the Arris has two WAN ports and 3GB ram. Not sure how much ram a modem really needs. I also heard the Arris gets hotter. I'm pretty stumped on which one to get. I'll be getting a netgear router to pair with it soon.

Is it better for the modem and router to be from the same manufacturer? Will I see a difference in the extra ram? Will two WAN ports benefit me in any way for regular residential use? What is the best one to purchase for use with Cox? They cost around the same right now on Amazon, so it really comes down to which is the better prodcut.

Can anyone who has experience with either of these shed some light and help me with this decision?

Thanks