Actually i get almost 1k gold from a full Kara run (except Netherspite) killing all trashes up to Maiden, since they're easly pulled/killed and give decent gold, then only those pull i cannot skip.
MC can be fun but half the bosses and trashes don't drop gold at all
ZG is far easier than MC (which is easy already) and gives more or less the same amount of gold (Aq20 is more or less the same)
Last time i tried AQ40 i was able to kill first 2 bosses, but was a real pain... not really worth it (and yes, you will probably need nature res gear).
Maghteridon is a LOT of fun and Gold, but you either need very good gear (to be able to use an unholy hybrid spec to have a perma-ghoul) or you're either gonna hit the enrage or (without a permanent pet) get mad at the boss despawning during the earthquake.
Doomwalker too is ~500 gold, but you have to find him alive...
I've never be able to get 4 person to help me open ZA, so i can't say anything about that... and i'm working on Morogrim Tidewalker in SSC atm (but i need help on the murloc trashes before him... the pulls with 2 healers result in an endless fight -.- i cannot win... or loose...)
EDIT: for Jerigothiel Is BWL really that easy now? I didn't even try cause i though 2nd boss would need to many people to still be interesting to go on with (as usually people don't come for one boss and then go away)... maybe i shopuld have tried :P