I may be biased, but I highly suggest Sony. This is because, in my experience, they do a better job of implement HDMI protocols (especially CEC) correctly. Chiefly, they do a good job of audio sync handshakes between devices (no lip sync issues!).  
 

Sony TVs have their own share of problems (no TV, unfortunately, is perfect), and every TV you settle on will be a compromise of sorts. Proper HDMI CEC implementation is a must for me, and Sony — in my experience — does it best. 
 

P.S. Until Arc supports multichannel LPCM (a promised firmware update at a later, undisclosed, date), I suggest setting the Apple TV to output only Dolby Digital 5.1 sound. This is because when sound output on Apple TV is set to Auto, it sends a multichannel LPCM signal to the TV, but the Arc can only process the stereo portion of it (unless the signal is Atmos, but that’s another story). This is not a TV problem, but an Arc problem, which will be fixed in the hopefully near future. 

@oriboaz

i was reading about the LG CX issue with LPCM as well as Sony A8H.

does this mean you don’t get atmos effects currently with apple tv 4k content ?

I also read on a reddit that there was a combination of settings that allowed the TV to mediate the signal allowing the compressed version of atmos to work with the Apple TV 4K source.

I may have misunderstood the post though.

I am buying a TV and home theater setup soon. If LPCM is confirmed as avoidable or fixed by the time I am ready to pull the trigger, the sound will likely be a 5.1.2 sonos. If not I will use components for an atmos setup. (All previous systems have been wired components for me. Just wanted to avoid the hassle)

Adding to this has anyone had issue with HZ1000 Panasonic with DOlby Atmos on the native eARC port?

As I am going towards panasonic as an upgrade.

I have three arcs, two are paired with Sony A8H’s (55” & 65”), and one is paired with a 65” LG CX. I hate my Sony TV’s; they’re garbage IMO. I wish I had gone with LG’s exclusively. Two main reasons:

1. When using an HDMI connected source (apple tv, game console, etc..), my Sony TVs will display a black screen with a Bravia logo in the lower right corner. This happens after 30-60 seconds. I can still hear audio but don’t have video. You can google this issue; several others are reporting the same issue with no clear resolution. The issue has something to do with using eArc devices with Sony TVs.
2. This next issue is not as consistent but still happens. Audio through my Arc will cease. The only way to restore audio is to switch “Audio Output” on the TV to “TV Speakers”. After doing this, the TV will recognize the Arc and automatically switch back to “External Speakers”.

My Sony A8H’s are both up to date with the newest firmware as of this post. As for my LG, not a single issue with the Arc and other inputs. If you’re debating between a Sony and LG to be paired with an Arc, go with an LG!

I have CX77 playing nicely with Arc. I was very sceptical when planning tv upgrade seeing all the posts about various lip sync issues and audio dropouts/crackles and pops. So far so good. Atmos sounds a worthwhile upgrade over previous DD5.1

I’m only using built in aps but after a couple of weeks so far not had any issues beyond the initial setup (which seemed unusually problematic - 1st Sonos product I’ve ever had issues setting up!) but so far only issue has been needing to adjust the sync setting for playback via the Amazon app. ATV, Disney+ and Netflix all playing nicely.
 

I’ve not used the hardware ATV with it yet (don’t see much point as the built in app does most of what I use week to week). Will test out the PS3 soon but I rarely use BRD any more so not fussed if it won’t play nicely. 

I did some additional research and testing this weekend. I found that Sony had a new firmware update available. Download and update through the TV would not work. Firmware updates don’t necessarily push to the TV when they become available and cannot be pulled, you have to conduct a manual update (download to USB, plug-in to TV). After all this work my TV is updated but my original issue persists. The dreaded Bravia logo and black screen are still present on all HDMI inputs while using the Sonos Arc.

I found a workaround, but it's not an acceptable solution in my opinion. If you disable eARC on the Sony TV, the black screen and Bravia logo will not come up while using HDMI input. The drawback is that the TV will not output higher quality audio to the Sonos Arc (e.g., Dolby Atmos). If you want to try it with your Sony TV, try this:

Settings → Display & Sound → Audio Output → eARC mode → Off

Hi mjm05 - Sorry to hear about your issues.  I have a Sony A8H and have none of the problems you are experiencing with your tv and Arc. In my settings, earc is set to auto. Previously, I had the intermittent audio popping/drop outs that have been widely reported when I used my tv’s streaming services. I contacted Sony and we tweaked some of my settings such as changing RS232C control from Via HDMi port to Via serial port, turned Bravia sync control off and changed my hdm3 input to Standard Format. I only have one device connected to my tv, which is my Sony UBP-X800M2 4k blu-ray player. That hdmi input is set to Enhanced Format.  I get full uncompressed Atmos from my 4k Blu-Ray discs and great sounding LPCM 5.1 from my DTS Blu-Ray discs. No problems getting Dolby+ Atmos from the streaming services as well.  The one issue I had was that the Sony A8H tv update released on 12/1 did not immediately fix the audio popping sound.  I had to do a factory reset, which was a pain but after the factory reset it fixed the issue.  I have not downloaded the recent tv firmware update, which apparently was released on 2/23.  Since you have, and are still experiencing problems, I would consider trying a factory reset and/or contacting Sony directly (if you haven't already).

Actually, my Bravia Sync Control is activated. It is greyed out but on. This may have something to do with the fact that the only other media device (other than the Sonos Arc) connected to my tv is a fully-compatible Sony Blu-Ray player.

Coincidentally, when I turned on my AH8 this morning, a notification popped up indicating a new software update was available and asked if I wanted to download it, which I did.  So even though new updates are not automatically downloaded, there is at least an automatic notification, but you need to have the option to automatically check for updates enabled in the settings.

Total opposite of my experience and almost everyone else on here. Have a look at all the threads with lip sync delays and other issues with LG TV’s.

The LG CX can’t even pass LPCM 5.1 properly from connected devices to a Sonos Arc. I went through multiple LG CX’s and they were buggy as hell. Settled on my Sony A8H and loving it. I’d never buy an LG TV again.