Luke got his ass kicked the first time he fought vader(and if you can remember vader was trying to convince luke to join him as well). The second time he fought vader there was a time skip between the 5th and 6th movie luke was a jedi knight by then. Also the only way he beat vader was by using his anger. Im sorry but no matter how I look at it Rey is too op.

>>#198, There's also the element of unpredictability in Luke's fighting style. If you watch, he LOOKS untrained in combat. He swings wildly and wide, bashing and smashing the saber down almost like it's a mace or hammer, compared to Kenobi and Vader, who handle their sabers like professionals. His combat style kept Vader on the defensive for most of the fight, as swinging to attack would have left him open to the overhead slash that would have absolutely come.
But yes, there was absolutely a skip of at least a few months between Episode 5 and 6, where Luke trained on Dagobah. Not enough to become a pro, but long enough to learn the basics well enough.
Looking at Rey, we are never shown any evidence of training in movie. The only source of this info is the extra little book that was put out, which seems like the usual cash-grab with afterthoughts added that is par for the course with Star Wars.
tl;dr Rey was OP, Luke was underpowered by unpredictable/lucky.