Not reading all the comments to see if what I say has already been mentioned, but the best way to earn exp is always daily roulettes and then spam high level dungeons (except those 50/60/70/80 dungeons give crap exp, so run 47/59/69/79 dungeons if you're lvl 50/60 etc...)
71-80 bozja is great exp if you have access AND if people are there farming stuff. If you're solo it'll be slow and boring. When it's busy you can speed run fates for like 300k exp per fate iirc) which seems like nothing but they go fast and add up real quick. I used bozja to level dps in early ew since queues suck.