I have owned the Yongnuo system for a couple of years and recently purchased the TX unit. As you will see the YN system is not satisfactory for my use.
The YN system has evolved from using identical YN622N units one for the camera and others for remote flashes to a system using a yn622TXon camera and YN622N with the remote flashes. Two or more YN622N work perfectly with cameras of the D7100 era but become erratic with the D810 . iTTL and manual are available with both systems the powers being set on the camera transmitter unit. The buttons are easy to knock so you are always checking you have the green leds matching TX to RX... Using the YN622TX on the D810 removes all the strange behaviour but the evolution leave two big flaws. The YN622TX has no shoe to mount an on camera flash, the system does not like any sort of cables so its not possible to have the TX and an on camera flash. That is essential for me at weddings as I want one flash on the camera over the lens and another behind the bride. The other problem relates to the YN622N which has a foot with pins (for when its on a camera) but that means you cannot mount it onto any sort of metal shoe and it has no tripod boss. A plastic adaptor is available. The Godox system sorts all this out and at a similar price (one TX and one RX for $60) .The TX has a flash shoe,it does not seem to mind cables between it and the camera or it and the flash gun. Additionally it has an on/off switch for a focus lazer. You don't need a remote unit to actuate the lazer ..ideal for churches . The RX unit has a shoe fitting and a threaded boss with no pins. Both systems are easy to set once you get your brain switched on.