I once heard it said that more "cool features" are just more things that can break. For the most part, I agree.
For example, an ATO sounds like a great thing, especially with my current back issues - but I've heard of far too many instances of catastrophic failure. It's just not worth it to me.
On the other hand, a good controller sounds excellent - not to replace observing the tank, but to alert me if there's trouble, like if I'm away and the tank cracks, or if my heater fails (which happens to people far too often.) Being able to check my params without fighting with the test kits would be a nice side bonus, especially in an emergency (omg, all my fish are at the surface - is it O2? Ammonia? Maybe soap?!)
I'd also like to note that my params are pretty decent right now. As of last test, I was reading 5 nitrate, 1 phosphate (down from 2.) I don't have a skimmer, reactors, pellets, sump, anything at the moment (still pre-upgrade due to a bill issue)...just an old-style Tetra Whisper 60 HOB, a plastic thermometer, live rock, one Petco powerhead, and two heaters. My lighting, while insufficient IMO (mainly because it's too short), is a 24" white and blue two-strip LED. I dose Dr. Tim's Waste-Away and have begun dosing vita-chem because my struggling diploastrea responds well to it. I did add a half-dose of PhosGuard to the HOB a couple days before testing. I also feed heavily. That's it.