value of load lift controllers?

We don't have enough information to give you sage advice.

What chassis?

What are axle weights vs GAWR's.

What are you trying to correct/improve?

I added air bags to rear of my 2004 Fleetwood Terra to raise the back enough to get it up my driveway and into my backyard. I also installed the compressor so I could do the filling from the dash. Since they were there, I used them to set the coach level when loaded. To my surprise, the coach handled much better. Often, just like in DP's, setting the ride height correctly (front to rear level of the coach) makes it handle as designed (correctly).

I had air lift bags on my truck with an "in-cab" controller. It made leveling the load a breeze and it made fine-tuning the ride even better.
I felt that the ride was significantly improved.
If you are adding the bags, get the controller!

Bill

Air bags helped out a smoother ride in my front, 08 Ford Chassis, also gave me more lift in back when bringing my double deck trailer.

I assume you are talking about air bags in addition to your springs. They won't do much for making the ride softer but will help if you are not level. They also will not increase your carrying capacity. I had them on a 35' Pace Arrow in a '96 P-30 chassis and was happy with them for levelling the coach.