Naturally, the ones that are directly responsible for the survival and propagation of the human race will be the strongest, emotions exist to incentivise useful behaviors. The primary ones are fear, aggression, and lust. Fear, to escape danger. Aggression, to eliminate danger and seize resources, and lust, to create the next generation. If you consider hunger and thirst (and tiredness) as emotions (I don't, but an argument could be made), then those would also probably be among the strongest as well, if not definitively.
Loneliness and love (of all it's different varieties, romantic, platonic, familial, communal, etc) are contenders for the title as well, and they come in a set. They are meant to incentivise communities sticking together, which is beneficial for survival via passing on knowledge, allowing young to be raised in a safe environment (and sometimes inciting self-sacrifice for the sake of those young, who carry the future of the race), and supporting members while incapacitated and temporarily unable to gather food (or perform other tasks) due to injury, disease, or pregnancy.
Happiness and sadness are both auxiliary, they apply widely to many different aspects of life, which is a different kind of strength, but they mostly exist to encourage and discourage behaviors passively, rather than incite direct action.
Guilt and shame and embarrassment are important for maintaining the tribe by punishing behaviors that could be problematic to it as a whole and ensuring that no one acts to out-of-place so as to maintain tighter bonds between members.
I could go on. Ultimately it's pretty fallacious to try and put any one emotion above the others, they all serve vital purposes. And which one is a more powerful motivator/driving force depends heavily on the individual.
The desire to be a dragon.
Idk about that, a lot of people would rather be catgirls. Puppygirls and foxgirls are also pretty popular.
