Best Game Boy Game of all time and Why?

For sure GTA

 

Hard to argue against TMNT since it is considered the best game for Gameboy.
I remember playing it as a kid and I actually think it was the first game I was consumed by.

 

I just read GTA 6 is also coming?

Reference: https://www.gamerevolution.com/news/402387-report-gta-6-release-date-teased-by-online-message
https://www.gamesradar.com/gta-6-release-date-news-trailers-map-gameplay-rumours/ also GTA 6 Release Date

 

destiny 2 ascendant challenge will also a good option.