Which of These Two Softeners Would You Use?

I have two softeners available and need advise on which one I should use based on your opinion?

Cole & Massey Model Pem45YZ-DL
With a ? Valve and a 10x44 tank

OR

Water Right / Impression Series Model IM-1044ME
with a Clack WS1 valve and a 10x44 tank

One is the Fleck 6600 valve, still a good valve , the control is out of production but another powerhead can be used in its place.
The other is a great one from Clack...
Both valves are good with a good history and life.
what is the water quality that either of the systems would be dealing with?

Well water with 21 grains of hardness and .06 ppm iron content no odor with 4 people in the household. The Fleck softener is 9 years old with original media and is currently installed in my house. The Clack softener is 6 years old with new media. So would you remove the Fleck softener and install the Clack softener?

Do you know what the capacity of the Clack unit is?

No other than the tank size is a 10x44. How do I find out?