The ones I think I played most are: The Goonies, Maze of Galious, Nemesis 2, King's Valley 2 and Konami's football. When I upgraded to Turbo-R I played Illusion City, SD-Snatcher and Usas.
Nowadays I play KPI ball and Xak and with my children Quarth, blade lords, bubble bobble and Salamander
Zanac, space manbow and aleste2. Those three always kept me up. I discovered the latter two after my msx revival period so my ultimate childhood waste of time was definetly zanac. Later on in my childhood I played a particular platform game at friends that was not available on msx. Solved that problem 20 years later
Oh! I've forgotten Aleste2, thanks Daemos to make me recall it. I played many hours. I still haven't discovered what makes you get the circling shield with different colors. I think it is related on how long you haven't been killed. The basic is the red one, then comes the blue and I think that then the black one. And I also recall the magical spot in the boss of stage-4 where you aren't killed
Nemesis 3 got some serious time spent on it back in the day, followed by f1 spirit and Kings valley 2. The game that possibly took most of my time up was THE BOSS by peaksoft, I loved to pick a division 4 team and take them to the top of division one and into Europe!