Keep in mind these are the recommended minimum numbers to carry all of the loot back.
Lvl 1- 8k warriors
Lvl 2- 14k warriors
Lvl 3- not 100% sure i normally skip this and start farming with ballista and transports on the lvl 4.
Lvl 4- With the new changes to defence the numbers have got boosted soo about 700 ballista and 350 transports.
Lvl 5- 2k ballista and 500 transports.
Until they decide to change stuff back those are the only ones worth farming. The respawn for the resources is every 8 hours.