Originally posted by tahoejeepmom I need a new flash.
If you plan to use the flash off-camera as well, I'd get one that allows you to control its power level from the camera position.
The Godox V850 supports remote power level control (with an extra external receiver add-on that does not need any batteries of its own though) and is just the ticket if you want very fast recycling and extreme battery longevity without involving the cost and the bulk of an external battery pack. Note that there is a cheaper version of it, called the Neewer TT850.
For single flash power control, the Godox transmitter is adequate, but if you want room for growth than I'd recommend the Cactus V6 trigger which has much better usability once you go past one light source.
The V6 should be able to control the power levels of all the flash models you mentioned (perhaps not the Sigma; remains to be seen).
You'd need a V6 for each flash you want to trigger, and one more to trigger/control the former.
You would not have to add a V6 to the RF60 flash which has a built-in, integrated radio receiver that also supports remote zoom control on top of power level control (plus some more advanced features like an HSS sympathy mode).
Unfortunately, neither YN560-III nor Godox V850 can be remote power controlled by the V6. The Godox V860C, however is supported and uses the same battery as the V850.