The AppleTV is an excellent choice and hopefully you’ll like the universal remote with it.
I always had issues with FireTV sticks and I always thought it was poor WiFi performance on them. Now I have a 2nd Gen FireTV Cube and it has worked flawlessly both wired and WiFi. I like its remote a whole lot better.
I did try the 2nd Gen cube a while back. It was fine, and it still has the flexibility of side-loading apps like the Sticks. The remote was the same as my Firestick 4K remotes, which we generally like. I didn't have any networking issues with it. It didn't seem like it was worth the extra cost vs. the 4K stick if you already have the stick, unless you want to use Alexa for more things, then its true value becomes apparent.