Fractals - Drops any core or lodestone from end chests, doing daily's up to lvl 30 can make this very profitable with a good group/guild
Dungeons - Specific dungeon drop specific core/lodestone sets. Multiple chests per path can sometimes make this even more profitable than Fractals if you end up getting more cores to transmute into lodestones. Doing paths multiple times per day net you less and less tokens, but are very fast and can be done for full reward on different characters.
Mobs - Very specific enemies drop one type of lodestone each. 78+ for lodestones(Sparks in Malchor's only specific mob for <80), 65ish+ for cores.
Orrian Jewelry Boxes - Current drop research into O.J. Boxes make this the least likely of ways to garner you lodestones, but if you need to transfer Karma, that .10% chance might net you something. http://wiki.guildwar...y_Box/Drop_rate
I say them in that order because that's the order of likelihood I've seen in which I've gotten lodestones. I don't farm dungeon paths or do anything in Cursed other than the DE chains, so my list is probably in the wrong order for others. I'm not a grinder or a min/maxxer by any means, so I usually do everything except high-level fractals and the odd dungeon, if I think the group needs more support, in all MF gear with 130% MF incl nourishment. Blast me if you will, but I've had great success in MF gear and I swear by it.
Edit: changed mob level for Sparks to 78+
Edited by Kor, 15 February 2013 - 05:57 AM.