Including DLC, micro transaction purchases, etc. If you got a game for free, please also list your non-infinite next best.
For me it’s Team Fortress 2. $100 total spent on hats and the Orange Box back in the day, 4200 hours plus of fun, meaning 2.3¢ AUD per hour. Initially I thought DotA2 would be my best but it turns out I’ve spent a lot more money in that game than I thought…
My worst is God of War: Ragnarok. Bought it full price for $95 AUD, only played 2 hours and hated it, meaning $47.50 AUD per hour.
Probably CSGO, because I made at least 100€ playing that game for ~500 hours, and even mostly enjoyed it.
As for the worst, kinda tough to say, since I bought so many games and it’s probably one I can’t remember. Only one I can think of right now is Monster Hunter 3 for the Wii, which I bought the collector’s edition of, only to realize I really don’t like Monster Hunter games.