If you want the absolute best Apple TV experience, and you have a 4K TV to do it justice, then the Apple TV 4K is the best option. This comes in 32GB and 64GB versions. Most people will probably find the cheaper 32GB version offers enough storage for their needs, but you may wish to pay more for the 64GB version if you download a lot of apps, particularly games.
However, if you don't have a 4K TV and have no plans to buy one, then we'd recommend the 2021 Apple TV HD, which is around $30/£30 cheaper. This comes with many of the features of its pricier sibling, including the new Siri remote, but it's only available with 32GB storage and there's no Dolby Atmos support.
Meanwhile, if you want to save some money, the 2017 version of Apple TV 4K is seeing regular discounts, and it actually offers fairly similar specs. The processor doesn't have the ability to play 60fps and it has the older Wi-Fi standard, but if you find a saving that sways you, it's still a great TV steaming device.