Good units, SUPPORT SUCKS.
If your good at figuring things out yourself, they are Great. If you need your hand held go Apex, Better support bigger user community to help answer your Questions
My ReefKeeper light with SW5 is currently doing the following.
1: Heater Controller: Keeps Temps Stable at 25C
2: Fan Controller, Turns Fans on when temps get higher than 25C
3: Skimmer Controller, Turns Skimmer off at Feed Mode, and turns it back on 20min AFTER feed mode
4: Pump Controller, Turns Return Pumps and Power Heads off during Feed mode or Maintenance mode
5: ATO, Auto Top Off, Plus ALARM when RODI Container is low (Beeps and Flashes so I know to Add water to Top Off Container)
6: Maintenance mode (When doing water changes, or working on the Tank, Flip a switch and Pumps turn off until switched is turned back on)
Getting things like the ATO to STAY OFF after Feed mode as a PITA to get working. as you can't add a Delay to a switch. But found a way around it.
The APEX Guys have it easy when it comes to programming, ReefKeeper people post questions and get ignored both on this forums, on the DA Forums, and when you email or call DA for questions.
So Cost: The Reef Keeper wins.
For Support, Programming, TONS of Modules, Apex Wins.
Me I like a Challenge!
Really depends on what you need the controller for. and what you want it to do.