At the time of writing this the V850 are really the only inexpensive remote manual speedlite currently available. And likely the only Lithium-Ion speedlite to be available for a while until others catch up.
The remote manual flash coming from Cactus in a few months will likely be the most comparable alternative we know of at this stage (though don’t expect Lithium-Ion power).
The YongNuo YN-560 III are likely the flash most people will currently be choosing between though. The YN-560 III should have actually been the first inexpensive remote manual speedlight available, but YongNuo have been very slow to release a transmitter which will enable the remote power control already built into the flash.
The YN-560 III are still a great little flash for what they are. Though the V850’s built quality alone is better, and considering the flash without battery and charger (as the YN-560 III comes) does not cost that much more, the V850 come out pretty favorably in comparison. That’s even if they didn’t have the Lithium-Ion battery, currently available remote transmitter, and HSS option.
Where YongNuo have also dropped the ball a little with the YN-560 III, is that they are not directly compatible with their other popular systems like the YN-622. So there is no real incentive to not go with another brand option like the V850, as they are no more or less compatible with YN’s other systems.
How well Godox will integrate the V850 into their own coming systems other than the current manual Witstro also remains to be seen.