I used Apex EL + Trident on my older tank. But I choose Hydros + Alkatronic over Apex on my new build.
Price wise depends on what you need.
Apex EL is $500, one pH/ORP port, 8 outlets. $280 for every 8 additional outlets
Apex is $800, two pH/ORP ports, 8 outlets. $35 per additional outlet
Apex Trident is $600, reagent is $0.13 per test, $200 per year.
Hydros Control 4 is $450, two pH/ORP ports, 4 outlets, $40 for every 4 additional outlets
Alkatronic is $900, reagent is $0.04 per test, about $60 per year.
So if you need more than one pH/ORP port, Apex + Trident is the same price of Hydros + Alktratronic, with a lot cheaper running cost and expansion cost. Apex EL and Hydros Control 4 + additional power strip is also the same price, with an additional ph/ORP port. Also adding temp probe for Hydros is easy, just buy another probe, since temp probes and level sensors all use the sense port and there are 4. For Apex you will need to buy another PM1/2 module besides the probe.
Functionality wise, they do similar things. Apex is a mature system on an outdated foundation, Hydros is a modern system yet to be matured. Both have pros and cons. Apex have more accessories readily available, depends on what you want to do. Hydros is still missing many, though they said they will catch up within a year, but who knows.
Software and programability is easier on Hydros with real no code required while capable of AND/OR logics. I have a bit more write up in my
build thread.