1. Classes with personalities
There are no boring, identical characters. The Doctor, the Spy, and the Soldier with the flare gun each have their own style and quirks.

2. Relatively easy shooting (and melee)
You can learn to shoot in five minutes, but it takes hundreds of hours to become a pro. rocket jump, Spy's backstab - there's room for growth.

3. Free, but without pay-to-win
Everything important (weapons, abilities) can be obtained simply by playing. You only need to pay for hats (but you can live without them).

4. Calm
No one yells in the voice chat like in CS or Dota. (although they sometimes do) I have 1000 hours in Dota2.

5. A bunch of modes
Official maps are diverse (I especially liked the castle map)

6. Graphics that don't get old
TF2 looks like a cartoon, so even after 15 years, the game doesn't feel old.

7. Valve hasn't abandoned it
Updates are rare, but the game still works, gets fixed, and even occasionally receives new features.
Good luck 🍀