I'm an overlevelling turd when I play FF so in FFV I like to get the most OP abilities I can as fast as I can. Call it a sickness. For me my favorite ABP harvests were in:
Very very early in the game: A strip of land directly southeast (you have to sail to it) of the Wind Shrine. The Bandersnatch's there (can't remember how many to a group) drop 3 ABP total, which is very high for this point in the game and they aren't difficult to kill at all.
A little further in: The Chimeras in the desert are nice, and with two-handed most die in one or two hits, library of ancients is right there for a free fix even if someone dies.
In world 2: Of course, the Objet d'Arts in the basement of Bal Castle. This just can't be beat; you can Iainakui them, but I had my guys each set up with Summon and after 3 Ramuh's they were almost always dead. I mastered about 8 or 9 jobs this way, pretty much had me set for the game.
Combined World: Haven't found a really great one yet, though everything tends to give a lot of ABP. Still scouting for good locales and easy kills (Requiem on Undead, that sort of thing.)
What about you guys?