Forgetting the 4K video resolution capability I'm wondering if the
4K model of the ATV is an all around better client for Channels and/or
Channels DVR? Ie..faster decoders , more bandwidth, faster cpu that sort
of thing; I'm considering moving my wife off of ROKU onto an ATV (she of
course will get the older model..heh heh); she detests the ATV remote so this
will be a hard sell at best
Why not get a Fire 4K stick? I have that and an Apple TV 4K and can’t tell a difference.
The ATV4K is the best streaming device unless you want YouTube 4K. The remote takes some getting used to, and we used to hate it but have grown to really enjoy it.
Thanx..Tim..for the reply..Did you max out the onboard memory of
the ATV4K for increased buffering capabilities?
I have both a ATV and a 4K, and they both work swell. No problems with buffer length. I think the most important difference is the Gig interface, it’s more responsive with the bandwidth hogging streams.
There's really no need to get the larger sized one.
I would wait a few days. Sept. 10, 2019 the Apple Event is "rumored" to announce a new Apple TV.
MacRumors:
Apple TV
Code found in an internal build of iOS 13 references a new Apple TV 11,1 model, suggesting Apple is working on an updated Apple TV. Little is known about the new device, but it could feature an A12 processor. There's no word on when we can expect a release, but it's possible this new Apple TV will debut at Apple's September event or later in October.
On the issue of the remote - We have have an ATV 4k connected to a VIZIO 4K and are able to use the VIZIO remote to control the ATV over HDMI (ATV mounted on back of TV). So that may be an option depending on your TV model/capability. Note the opposite works well also - ATV remote turns on TV and controls volume of VIZIO speaker bar connected over HDMI and optical for the actual audio (ARC is only on HDMI1 and that is also the only 4K port on my model - a bit of a hack but works).
If this rumor is true, I'll be selling an Apple TV 4 and 4K if anyone is interested. 
I doubt it. They are going to release a new TV app though, with subscriptions to streaming channels.