Rey vs. Bella Swan: The Mary Sue challenge
This is not a fight between the two, this is to determine who's the bigger Mary Sue. Who was showered with more favorable coincidences and luck? Who had an easier time doing and achieving stuff that they never worked hard for? Whom did the universe favor more?
Bella. She essentially became the Superman of the vampires for no special reason. Her toughest time in life was moping around because her boyfriend left to do a suicide by cop/Volturi in New Moon. Although the whole giving birth a vampire whilst it's trying to rip you apart and breaking your back is probably more painful than anything Rey went through.
Rey was abandoned by her folks, had to make ends meet on Jakku, trained with a staff, and learned and honed her skills as a mechanic until she got linked up with Finn, the Millenium Falcon, and Han and Chewie and then went full force cheat code at the end of FA.