The control for all aquaero 6s is the same, the only difference is input buttons, remote, etc.
The LT would be the most economical of the aquaero 6s.
If you have a single loop it may be more effective to use an
OCTO, as you have 8 PWM ports as apposed to 4 on an aquaero 6.
If you have a double loop, it may take an OCTO per loop, as the OCTO only has one flow sensor input port.