Impossible Mission (both one and two)
Beachhead
Ghostbusters (Name: ANDY and account # 777 😄)
Raid over Moscow
Pretty much all the Epyx games (some of the only sports games I've ever really enjoyed)
Montezuma's Revenge

Of my six disk boxes filled with 50 disk's each, those were my goto games on a regular basis. Countless hours of my 80's teenage days wasted on those games. I still use my Slik Stick, Epyx XJ, Wico Ergo, and TAC-2 on those games, but on my PC with C-64 emulators and a USB to DB-9 adaptor. I keep my C-64 packed up with my much of my other retro consoles and computers. I can deal with the emulation of SID not sounding exactly like my original breadbox C-64, as its close enough for me. The speed of loading games via the emulator is well worth the minor sound disadvantage. But in the future, I will get some sort of flash storage adaptor for one of my C-64's and start using it.