Imo fire warlock rotating between TZ chaos, TZ tombs for high density and TZ andariel + meph + diablo, flayers, halls. It's raining shards so they're dirt cheap, just keep sharding them at P7 and do good rotating TZs with high density (halls, flayer etc). With enigma, gheeds and new jewel, couple with mf scs, you're good to go. May choose to ignore heralds after getting those sunder chronicles, as they're current drop rate is bad and not efficient for chronicle.
TZ andariel will be the fastest
For TZs, any TZ are fine which you can kill fast.
MF and clearspeed are equally important, only that mf has a diminishing return so if you have 150-200% thats fine.
Myself i like round around 250-300 mark and still be reasonably fast (this is really depends on characters, some of mine has 550-700 mf and some 150)
This is decent information, sending 25FGs each

Would love to hear more Build-Recommendations for high denstity TZs - especially non-WL ones