Thore Hund's criteria are good to take in account.
Anyway, that kind of ranking depends on the point of view you adopt:
Personally, I'd put over the 10 most important figures
1-the sumerian whe ever invented the wheel
2-The one on hte neolithic times who got the idea of domesticating Cats/dogs as they are good company
3-The minoan who conceived the first urban watering systems . I cannot stand without my daily shower specially during this hot summer!
4-Archimedes
5-Hippocrates for giving start to the western medecine
6-Aristoteles
7-Thomas Edison (or rather his predecessor Joseph Swan) because I presently cannot conceive life withouth electric light
8-Alessandro Vlta because his voltaic battery is on the basis of the further developments in electricity
9-Alexander Graham Bell (all though I hate when the phone rings at work every minute, on the other applications fields I foud it quite useful
)
10-Henry Dunant for his foundation of the INTL Red Cross (ridiculously copied by the mosleem monkeys and their INTL RED CRESCENT MOON