NVIDIA Shield Pro (the 2019 model is the latest version) with a couple of customizations STILL is the absolute best for avoiding ads.

It is the most powerful outside of the latest model AppleTVs, but with the added benefit of being completely customizable.

Personally, I HATE ads, so I use a combination of customizations to eliminate them completely.

1. A custom “launcher” - this is a little weird to wrap your head around if you’re not familiar with Android OS devices, but it basically means “replacing” what you see when the device turns on. A few years ago, Google couldn’t help themselves and started adding more and more advertisements to their “home page” for the Shield’s default launcher app, so I switched to the “Wolf” Launcher and have never changed, though I would probably recommend “FLauncher” now since you can still (at least last I checked) get that directly from the Google Play Store without any “side-loading” (which means to install things from non-Google sources)
2. I love YouTube, but hate ads, so I downloaded and installed a 3rd party YouTube client called “SmartTube Next” - which although DOES require a side load installation, COMPLETELY ELIMINATES ALL ADS, AND in-video sponsorships, and even intros and other annoying filler content in some more popular videos.

The side-loading part makes things a little more scary/difficult to setup but I promise it’s worth it and there are always updated videos online on how to do this safely and securely.

I just set up like 8 of these things a few weeks ago for my brother and he loves it. Nothing is laggy or slow, no ads, and it integrated into his Smart Home stuff effortlessly.

One last note - a custom launcher can replace the default one (rather than run alongside it) by grabbing and installing “Launcher Manager” - another side-loaded app.

Running Jellyfin through a Roku works wonderfully. Jellyfin is a FOSS alternative to Plex and ran great on Roku, but ran poorly on Firestick, so it might just a Roku vs Firestick thing there.

Something else to consider is just buying a really cheap laptop for less than $200 or something and running Plex/Jellyfin or even just use your home network and play everything through VLC via HDMI on the laptop. You could even get a Chromebook and run Ubuntu on it and find an option for close to $100. A laptop option works well because you get to bypass ads and TVs operating system.

Google TV with Chromecast seems to work and it's relatively cheap. I do get occasional stutters every now and then. Honestly, if you want the most flawless solution, running Plex from a computer and plugging that into your TV will outperform everything else.

I have nvidia shields in basically every room of my house

Personally, I like having a full fledged PC connected to my TV. Currently I'm using a Beelink T4 running Ubuntu. The PC is under my direct administrative control, so no surprises with ads or other things.

Power consumption may be slightly higher than an NVIDIA Shield or Roku, but at 24w at full tilt for the Beelink it cannot be that much more.

The same Beelink machine comes with Windows 10 as well, if you'd rather have Windows.

I’m a fan of the Apple TV because I’m in the ecosystem. Plex works just fine for me there. And I love that my Apple TVs don’t seem to rot out as fast as Android or Google TV boxes I’ve used in the past.

That being said, someone else mentioned the Onn box, and that thing seems to have pretty solid value. I’d start there, too, if I was trying something non-Apple.

I will always recommend the Nvidia Shield. It works significantly better than any other streaming device I have or have used. You can also host your Plex server on it directly if that's a use case you're interested in.

Any Android TV device is going to have ads on the launcher now because Google sucks, but you can just install a third party launcher and set it as the default to get around that.

I assume you are talking about the Plex client or the server too? Client wise, the shield is still excellent as other folks have mentioned but I have been using Apple TVs lately, the client is snappy and works well. I have one of the first gen 4k ones and it plays everything I have tried to play. I got tired of the adds on the android devices and the Rokus have even gotten annoying lately so that’s what prompted me to switch.

ETA: in case someone is wondering, I also use the Home Assistant integration with my Apple TVs and it is superb.

Apple TV? No ads, works well with Plex, bypasses crappy TV “smart” features.

So... People are saying apple tv, but if you hate ads, and also watch YouTube, then this is not the way. If you go with something androidTV based, you can side load smarttube plus, which not only will block ads without YouTube premium, but it also has sponsor block built in, which will skip sponsored sections in videos.

I use a nvidia shield since it supports the widest range of direct play standards (h265, Dolby atmos, hdr10 / Dolby vision, support for refresh rate and output resolution switching, so on)

There's tons of other androidTV based boxes to go with, but thats what my research ~3 years ago brought me to get, and ive been pretty happy with them. The only con is that it doesn't like Ethernet cables that dont have a metal shielding on the rj45 connector. Not sure why, but yeah

i love my rokus. they can run plex and jellyfin without a hitch

Here is a greatbarticle on how to build your own streaming box with Kodi and a raspberry pi. You could also use a playstation or xbox.

I use Plex on my PS4. It runs great!

Rokus are cheap. So are Chromecasts. We have the same issue with our TV.

Hell, even an old laptop can be loaded up with Linux for a set top box experience via Kodi or Plex directly. You can use Kdeconnect to turn your phone into a mouse/keyboard input over your wifi.

If you have a XBox you could try Jellyfin as there are apps that run pretty well on it. There's also an Android app so you could grab a $50 TV box from AliExpress and do it that way too. It'll also work via a web browser.

Jellyfin is also open source with no subscription fees for advanced features nor all the bloat that's tacked onto Plex as well. It's got a clean interface that I quite like too. It can take a little more work to get running though.

Also, the reason it's running poorly is likely because Plex has no hardware encoding at all unless you pay for it. When I tested it there was a huge difference for me in playback smoothness with it.

Same situation, got a 4k Roku and it's been an absolute godsend for 3rd party apps!

So yeah, my vote is for a 4k Roku, I think they're a lot cheaper than an Nvidia Shield as well.

I will always recommend buying or building a small home theater PC (htpc). Then you get a wireless keyboard with a connected track pad and you are set.

If you are more tech savvy, you can save money and recycle by simply installing Linux on an old laptop/pc that you are not using and plugging it into your monitor.

Would Kodi be an option?