I use the Aquatronica and i love all the add ons and featuresthat the unit has. It currently has the most options with the Apex in second place.
I have it with dosing pump, leak sensor, ethernet (texts me if anything bad happens and sends a daily update aswell can also log into system from my cell and check up on and turn things on and off), salinity monitor, PH, Redox, water level, and temp and it controls absolutly everything in the tank and has programs to shut off turn off things depending on what the water params are. I really love the aquatronica but it was $$$$$ and probably about 2x all the other controllers listed.
If you wanted to save some $$$ and didnt care about add ons like the SMS module, doser or leak sensors then i would go with the Apex but if you had the money to blow then the AQ offers the most features but at a high premium much like everything else in the hobby (like getting a reef octopus over a bubble king).
If all you wanted was a light/timer controller with a ph monitor then i would go with one of the reefkeeper computers.