What NES or Game Boy (or even SNES) game do you think has the best 8x8 monospaced font?
You're aasking the "best" font. There's no such "best" font. Every game (or company) has it's own font, and that's what makes them apart from other games. I think it's good there's a variety of fong, there's no such thing as a best font.
Sorry it's not a best, but I can say the worst font I see that people really like to use is the Castlevania III English font. It was certainly a stylish font (certainly why they changed it from the fairly standard Japanese font) but I think it is actually barely readable (especially if you go all-caps with it). (though not the worst I've seen. Captain Ed has what I would suspect to be a terrible kana font.)
I fully agree, and it's funny noting that CV3 has a "gothic" font in English but normal font in the japanese version, and Super Castlevania IV is the other way around, the english version has a normal font, and the original japanese version a gothic font.
If you think it's hard to read, you have to look at old german books or printed text (pre-world war 2). They were systematically printed with gothic font, which is by today's standard extremely hard to read. But it looks great on logos and such, where it's still widely used (and not only in german).