No way to tell but the fact her strongest subordinates got stomped by pre-skip Luffy make me believe she is weaker than Law/Luffy and i think Luffy is stronger than Law, so:
1- Luffy
2- Law
3- Hancock
lol? And what they have to do with Hancock's power? If we go by that, Luffy is way weaker than anyone in the OP world because Usopp is a useless weak camel shit. Not to mention Hancock's whole country possess strong haki...
1. Luffy - gear second and third with his haki would make him stronger than the others
2. Hancock - Law has weaker haki than Hancock, he doesn't possess conqueror's haki either and I think he would have a hard time dealing with her DF power too.
3. Law - his DF needs a lot of energy (stated by him) and if his haki is weaker than the other two's I don't see him being superior. he is strong, but definitely weaker than an older/more experienced shichibukai, tho not much more.