Before they fight, right now if you had to judge...who is the greater fighter

Pacquiao is the greater fighter.
Based on what he's done.

 

Pacquiao has the better resume the better achievements and when you factor in his size and fighting style as well, clearly Pacquiao

 

It really isn't simple, you need to qualify what you mean as "great" because not everyone has the same definition. Some base it on number of titles, quality of opponents, record, excitement etc unless everyone can agree on a certain set of parameters everyone will give their own take on it and you'll end up having fans from both sides arguing but both not realizing they're talking about different things.