I have home built/designed studio strobes that sit in the closet after getting speedlights from Nikon(3 SB900's) and then adding 3 Yongnuo 568 ex flash for 1/6 the price. I am using the 622 tx flash controller with a bunch of 622 transceivers. None of them ever fail to flash at levels I set remotely and tested them up to about 300 feet. Yongnuo has flash with built in receivers for less than my individual 568 ex flash heads. The shift from studio strobes to speed lights is due to I can carry an entire outdoor light session with softboxes and strip boxes and stands by myself by public transportation. This set up did high-end furniture manufacturers new catalog( beds in classic styles from $20,000 and up, dining room tables up to $200,000) which were mostly reproductions of 17th through 19th-century museum pieces.
It is so easy working with light gear and so much less expensive. None of my gear has failed except 1 SB900 soon after I bought it, I repaired it myself since the store could not replace it from stock for a few weeks. A small surface mount capacitor shorted on the controller board, a $0.01 part that I had many of. There were some reports of SB900 overheating be only for those using rapid fire full dumps so Nikon fixed that by just dropping the power of full output on the SB910. I almost never need full dumps, it is never needed if one knows how to expose correctly. Even with modifiers it is not often needed to use full power that slows down recycle time a lot. At 1/2 power, an SB900 or 910 has zero recycle time.
My cheap Yongnuo speed lights and controllers are some of my best photo investments, just as much power as the top of line Nikon at less than 1/6th the price. They feel a little more rigid with thicker cases than the Nikon and the only difference is the beam focusing on theSB900 will go own to the equivalent field of view of 200mm. That might be of interest to a wildlife photographer but not for general photography or stuidio. If one needs a narrow beam in the studio they use grids and snoots for much more controlled beam size.
All of the controllers and flashes work perfectly with iTTL but 95% of multiple light usages is full manual exposure in sessions so that is only really useful when using them shoe mounted. When I do an event that uses a flash on the camera, I just pull a random speed light out of my bag, it makes no difference if a cheapy or SB900, they work the same.
The next step up in controllers is the 10 times more expensive Pocket Wizards which do no more. I have several of the Godox softboxes and their really cool universal flash/Bowens/mount that allows use of umbrellias , softboxes, mounting for light stands. They will mount a softbox and hold a speed light or a Bowens style strobe. Get a bunch of those. They are plastic but really strong and tough. They also have lots of essential modifiers....snoots, flags, barndoors, and grids.