Every thread hydros is mentioned I see
@n2585722 chime in, and that's probably a good person to get some information for in depth use of the system, if that what your trying to do with a controller.
Hydros can do some things, more than what I use it for, I have two systems running hydros with 3 xp8s 3 control 4, a few control xs and a few wave modules. But honestly I have it set up very simply and I don't care to tinker with it, it's definitely a entry to mid level tech for me and that's how I like it. It has some glitches from time to time and I think it's way overpriced for what I get out of it but hey whatever I'm able to have a monitor system without pulling my hair out trying to set it up.
I guess it depends on what you want to do there's tons of information out there on both so you should be able to make a decision after a bit of research. If it's cost making the decision that may make it a little more difficult, as I believe they are both designed to make you spend money, although having a hydros system I believe they are definitely designed to make you spend money on several modules and a system that is not quite there yet. They boast about the wiring system but honestly I think it looks terrible when it's full of wires that requires a board to keep them somewhat organized, I have 2 controller boards and still think it looks stupid with a bunch of wires sticking out the front, im not sure what else I can say I have no experience with apex but I can tell their monitoring and testing system with their proprietary reagents are a money pit, but I believe they both can be that. The newest products from hydros are just a joke to me and look absolutely ridiculous with dosing pumps and controller module combined into one device its so trashy to me.
Felt good to get some of that out but I still have the hydros and it works for me but like I said I'm not into tinkering and playing with the controller i use it very simply, but I guess it can be used more complex like others have stated and I've seen done. Again it's all up to you.
Now here's some pictures I've been meaning to tidy every thing up and get more organized and move the othe xp8 and control4 to the board but like you know life happens so yeah all those cool wires sticking out of the front look the way they do, im sure I'm not the only one, if you like to organize wires and make things look pretty you'll have fun with the hydros

and you'll need several modules they way they designe it. Good luck with your decision!