I want to say I am a Hydros user with Zero experience with the other two (I do have knowledge on them as I have done a lot of research). My opinion IS biased, but will try to keep with facts and experiences only.
Also it isn't any less expensive than an Apex once a PH probe is in the mix and more than 4 outlets are needed.
This is the part I am confused about. If you need 5-8 outlets, you can buy the branded strip for a measly $40. If thats too steep, buy the non branded
Amazon one that is 99% the same.
Isn't the Apex power bar like $250 or something crazy? Doesn't that mean way more $$?
IF you need more probes (2 pH + 1 Temp for example), yeah... You are forking out a ridiculous $350 currently just to get more probe spots. I agree fully with that. They need to make a cheap module that has probe ports. I find the C2 absolutely worthless for me due to no probe ports. For me, I only need 1 pH and 1 Temperature currently. The C4 was a solid fit for my application.
I really think Hydros (with its current options), is for people who are newer to the controller game or with a single small to medium sized tank. The tank I use it on is a Red Sea XL300 (65g display). It monitors everything I currently want it to monitor minus a salinity probe.
With that being said, I have a 15g nano tank also. I absolutely find no reason to waste money on the C2, let alone the C4, for it. I don't feel like it would be worth it at all. They are on separate floors which means I wouldn't be able to connect them anyway.
Lastly, the wifi strips don't bother me. I have had zero issues with them locally. I DID set up a repeater that the C4 connects to. That may be a factor to my success? I HAVE lost connection to the cloud (internet) a handful of times, but has popped up no probs. I CAN see how it would be a huge red flag for many people. Definitely don't buy this if you are going to be stressed about your wifi connection. If you DO buy the C2/4, think about buying a repeater to connect it to.
Closing. Is the Hydros the best controller? Nah. Is it the best for me? I think? Do your research, watch videos on each, and ask owners. I am hopeful for Hydros.