Good Morning Tonya,
Honestly setting up an Apex system is rather easy right out of the box. In the Apex world, your 2 choices are the full Apex System or the Apex El. The EL is $200 cheaper and is missing a Salinity (Probe/Port) and Orp (Probe/Port) . It's also missing missing the 0-10v port which allows the apex to control external devices like Kessil LED's, Vario Pumps, etc. You can always add these features with add on modules later.
So to start you will be able to monitor key elements such as your Ph, Temp, (Salinity and Orp Full Version). Apex also gives you the ability to control all of your devices such as return pumps, heaters, power heads, lights ect. You will be using a platform called Apex Fusion where you will visibly see all of your Probe readings, outlets where your devices are plugged into and much more. Each Outlet will have a Digital Slide button where you can turn a device on or off, as well as have that button set to "Auto" where more advances programming can be done.
When I say Advanced, it's not as bad as one would thing. Simply as an example, You can take your heater for instance. You would set your heater to turn on at 78 degrees and off at 79 degrees. This kind of programming is super easy to set up.
If and when you decide to setup a controller, we are always here to help. You are never alone. Please Let us know how things work out.
I always reference the below video. It's a great way to introduce you to the world of controllers. I am not very familiar with GHL, at all. I can tell you Apex has a much broader market, user base and support group. As stated above by #Ditto one of my esteemed Control Advisor brothers, GHL does look to be very well made.