I've been playing since the NES and despite being from a low income family I had the luck of being able to play and own many consoles over the 3 decades of my life, plus some pc.
If you ask me right now? Resident Evil 4 (2005).
A before and after in gaming, to this day still extremely fun to play even for casuals but 20 years ago it was THE masterpiece. And everyone took notice of it, everyone played it, even players that didn't cared about resident evil. The gameplay was so good that it got photocopied by everyone right after in the action genre.
Arguably the last big innovator in videogames minus Minecraft and... PUBG (Fortnite did it better I know).
Try to NOT pick your favourite game, that's a different thing.
Well, I guess my answer could change depending on you how define "best," but I think my answer has to be Dwarf Fortress. I've been playing it longer than some posters on here have been alive! The emergent narratives of your forts and your dorfs combined with the constant drip-feed of updates makes it endlessly replayable. The main game theme has been my last-call morning alarm basically since I had a cell phone that replaced an alarm clock. It's a game I come back to time and again that has yet to get old. If anything, it's getting too complex for my stupid ass lol