Price: $25 for a Tile Mate, $48 for a two-pack or $70 for a four-pack
Tile has been in the tracking device business for almost a decade, offering multiple types of tracker tags depending on what type of item you want to attach them to. You can choose between the basic Tile Mate (the most similar to an AirTag, but with a small hole for easier attaching to keys and such), Tile Slim (a thin option meant for credit cards and laptops), Tile Stickers and performance and combo packs, as well as exclusive and limited edition designs. Each product is available in different colors and pack options.
Tile has a dedicated app -- tapping Find will ring your Tile if it's nearby. It also works the other way around. If you double-press the Tile button on the tag itself, the Tile will make your phone ring. If you're out of range, the app will show the last place your Tile was located. If it's really lost, choose Notify When Found to get help from others using the Tile app anonymously (this is similar to Apple's Find My network feature).
The Mate can attach to most key rings, and offers a 200-foot Bluetooth range. In addition, the Mate uses a CR1632 replaceable battery and is water-resistant. The Tile Pro is the next level up and offers a bit more durability, 400-foot Bluetooth range, a louder ring and a replaceable battery. Tile's Sticker and Slim offer more variety for narrow spaces and actually adhering your tracker to an item. The Slim and Sticker are waterproof and also have a three-year built-in battery.
If you're looking for a variety of different tracking options and support for both iOS and Android, Tile trackers are probably your best choice.