I guess the question is what are you trying to track? You start off talking about Airtags, which is a device you would attach to something but then mention Find my Device, which would locate your registered device no attached device needed.
What device do you have? Google's Find my Device is a good app if you have something other than a Samsung. If you have a Samsung device Find my Mobile is a better option. It offers more options than Find my Device and is powered by Samsung, an industry leading device manufacturer with millions of devices in the field.
As for the tags you've mentioned, I don't know how popular Tile is these days with so many others in this field now, and with more and more people buying into ecosystems. You can still find tests and trials on YouTube for all of these devices. Not long ago I saw a string of videos showing Samsung's Smart Tags being sent to remote no where places and still being found. I've seen similar videos for Airtags, that were crushed in junk cars being sent to China.
I will say that as a former Tile user, I like my Smart Tags better. That's me and this is going to be a personal thing for each person, how they use their tags, and what their expectations are. Unless you plan to get a device with it's own cellular service they are all dependent on other devices, in areas with cellular service. If you're trying to keep track of your device I will say this about Find my Mobile, Samsung is claiming to be able to track devices that are powered off. I don't know if this is only certain devices, or how they are able to do this but it is an option that they released a couple of years ago and that users have to opt into for it to work.
Tell what you're trying to track, an object with a tag or a standalone device, like a phone, tablet or watch, and I'm sure the community will share our stories with you. In the meantime, I would direct you to YouTube where you can see all of these systems at work and get a feel for what your purpose would be and which it would fit best into.