Design
All three Roku Streaming Stick models are the approximate size and shape of a pack of gum and plug right into the HDMI port on your TV. It's a convenient and unobtrusive design. The Roku Ultra is a box you have to set down near your TV; it's not particularly large, but not as invisible as the sticks.
Winner: Roku Streaming Sticks (any of them)
Software
Each of these media hubs uses the Roku OS, the brand's media streaming and smart TV platform. It's a simple and accessible interface, with main menus filled with large, friendly tiles for apps. There are some ads and recommendations, but they aren't nearly as numerous as they are on Amazon Fire TV or Google TV streaming devices. Most major streaming services are available on Roku except for Twitch. Apple AirPlay is built in, so you can stream locally from your iPhone, iPad, or Mac.
Voice search is available through the remotes, though it isn't a full voice assistant like Amazon Alexa or Google Assistant. You can search for content and control a handful of first-party Roku smart home devices, but it's otherwise very limited, and you won't be using it as your whole-home voice control hub.
Winner: Tie
Video Quality
In terms of resolution, the 1080p Roku Streaming Stick is the only model in the lineup that doesn't support 4K. That makes it perfectly fine for older non-4K TVs, but for anything remotely recent (released in the last eight or nine years), you'll probably want one of the other media streamers.
High dynamic range (HDR) and spatial audio support varies on the higher-end Roku streamers. The Streaming Stick Plus can handle HDR in HDR10 and HDR10+, but not Dolby Vision. The Streaming Stick 4K adds Dolby Vision, but it doesn't have Dolby Atmos for spatial audio. The Ultra has HDR10, HDR10+, Dolby Vision, and Dolby Atmos, so it's the best choice if you have a good soundbar with rear satellites and height channels set up.
Winner: Roku Ultra
Wi-Fi and Networking
Wi-Fi 5 is the only way you'll stream with the sticks, though the 4K model has an edge over the other two with a MIMO configuration that can improve its range. For the fastest and most reliable wireless connection, the Roku Ultra features Wi-Fi 6. This standard offers better performance in all areas for 2.4GHz and 5GHz wireless networking, even if it doesn't break into the 6GHz band like Wi-Fi 6E and 7 do. You need a Wi-Fi 6 router to take advantage of it, but it's worthwhile if your TV is a bit far from your router, or if there's a large number of wireless devices in the area, causing network congestion. The Ultra is also the only Roku streamer with an Ethernet port, so you can run a wired connection to your router.
Winner: Roku Ultra
Power
Each of these media streamers needs power from some source. For the base-level Streaming Stick and the Plus, that can be your TV's USB port. Those sticks consume less than 3W, and can reliably run off of your TV. The Streaming Stick 4K might also work plugged into your TV over USB, but it takes a bit more power, so it comes with a USB power adapter to function consistently. The Ultra, which is even more electricity-hungry, has a dedicated power brick.
In other words, the Streaming Stick 4K and the Ultra require a free power outlet, while the Streaming Stick and the Plus don't.
Winner: Roku Streaming Stick and Streaming Stick Plus
Extra Features
The Roku Ultra comes loaded with extra features the sticks lack, mostly in the remote. The included Roku Voice Remote Pro features a rechargeable battery, backlit buttons, a mid-field microphone that lets you search by voice without pressing a button first, and a remote-finder function that makes it beep when you press a button on the Ultra itself. The Ultra also has its own USB port for playing local media from a drive, plus the ability to stream audio directly to Bluetooth headphones. The Streaming Stick models have none of those extras.
Winner: Roku Ultra
Verdict: The Roku Ultra is Best-Equipped, But May Not be the Best for You
There's no question the Ultra is the most feature-packed media streamer in Roku's lineup. It has the best remote, the best Wi-Fi, and the best HDR and audio support. It's also the most expensive and largest of the devices, and depending on your setup, you might not need all of those features.
If you just want to add streaming to an old 1080p TV, all you need is the Roku Streaming Stick, which costs less than a third of what the Ultra does. For 4K, the Streaming Stick Plus is one of the best budget-friendly choices, even if it lacks Dolby Vision; HDR10 and HDR10+ are still excellent formats (and if you have a Samsung TV, they still don't support Dolby Vision themselves, at all). Unless your router is far from your living room, the standard Wi-Fi 5 on the Plus should work just fine. The Streaming Stick 4K is a nice upgrade from the Plus that adds MIMO Wi-Fi and Dolby Vision for another $10, while still being half the price of the Ultra.
The premium Roku Ultra might be the top pick if you have high-end Wi-Fi and audio, or want the remote with the most tricks, but otherwise, one of the streaming stick models can probably fulfill your needs while saving you some money.