Helldivers 2 is the perfect model for a live-service game. The progression is brisk -- you can unlock multiple rewards after almost every session -- the cosmetics and premium battle passes can be earned quickly just by playing, and it definitely doesn't hurt that the game itself is an absolute blast.
If you haven't checked it out, #Helldivers2 is basically a 3rd person Left 4 Dead meets Halo with a Starship Troopers vibe.
