Mixed Up With Coke (Martin - 45) gives $18k and over 3k rep
Rooftop Rumble (Martin - 75) gives $25k and 4.5k rep
I've seen that the more crew members you do it with, the more rep you get on Hard. So it's giving like 5k xp per run and takes 20 seconds. This is how people are hitting rank 120 and higher already.