The important factors for any hand soldering application are temperature, repeatability and thermal response.

You need to solder at the lowest possible temperature that achieves high quality solder joints while maintaining your desired thruput on your production line. This is usually in the 700 - 750F range. But you also need to consider the repeatability of the temperature at the end of your soldering tip, it needs to maintain that temperature + / - 10F and idealy your station should not require calibration.

Finally you should seek a variable power soldering system NOT a variable temperature system. This will ensure that your operators cannot vary the operating temperature of the system and because it is variable power the tip temperature will remain fixed regardless of the load from the PCB. So they can go from joint to joint faster overcommin the thruput reduction associated with lead free solders.