Welcome. I think you'll be happy with any of them, but like I said, take a loook at the X68 - I have only seen it in a two-pack but you could for example get a 2-pack of the X68 and a single X20 node (they're sold on Amazon individually) if you decided you needed extra coverage in a dead spot. I think the X68 is the best tri-band from a value standpoint, and would make the most of your fast speeds if you're relying on a wireless mesh. If you have ethernet, there's no advantage to this system over the X60 or X20. The X90 is also very strong and tri-band, but much more expensive.
I just checked and the X68 is $249.99 + there's a $30 coupon at checkout on the US Amazon site! Great deal!