How much xp do you get in AFB? 40-50k (I really don't know i've only done 2 of them and I was sync..) Granted once you start AFB it's awesome 5 min of work for lots of xp..but AFB are always getting delayed between pulls and getting ppl there and all that crap. With pull time and changing jobs it takes prolly an hour+ start to finish. Then your done with nothing else to do..can try for wild card but then you have to start the pull BS again.
Abyssea is as good as you make it..I took 4 jobs from 75-80 in a single night with capped buffer and into merits. Time should never be an issue..last time I left with over 300 min left, and somewhere in the range of 220k xp in few hours.
tl;dr version..
An hour or 2 AFB on a good night is what 50k a run?
A few hours in Abysea is 180k~200k? And you can get skill ups along the way if you aren't key ***.
Abyssea > AFB