1) I've seen too many cooked tanks (one this year in fact) to recommend a single heater that can keep a tank warm on its own.1b) I prefer 2 or 3 heaters that total a bit more than what is required to heat the tank. This lessens the risk of one getting stuck on and cooking things, as well as the risk of a single heater failure making things too cold.2) Heating coils without built in controllers cost less, but then you are at the mercy of the controller.2b) Temperature probes fall out, end up dry when an ATO fails, whatever. Problematic if your house temperature is at all below your desired water temperature.I do use my Apex, but I only use it to control aquarium heaters that are self regulating (vs. a dumb heating element). I set them a couple degrees warmer than the Apex setting, and check to see if they are actually stopping as requested periodically. This lets me look at the duty cycle of that outlet to determine how often they run. If you set them a bit cooler than the Apex setting you can see if they are regulating correctly just by looking at the temperature graph. If you have a newer Apex then individual outlet current monitoring would give you duty cycle.I happen to like the Aqueon Pro heaters because they are plastic, have a light to show power, and another color light to show that they have reached their desired temperature setting. I have heard some reports of them getting stuck hot, and had it happen to one heater myself after ~6 years of use. On the other hand I have heard, and experienced, this with others as well. I suspect these are the same as the old Stealth heaters I liked (the plastic ones, not the exploding glass ones), but with a better adjustment knob.I really dislike the Fluval E series heaters. The switches go bad making it impossible to change the temperature. Worse yet they go bad in only one direction, so you end up with a heater stuck set too hot or cold. They also need a bunch of flow to not overheat and turn down unless you remove the plastic guard.Eheims seem to be well regarded. I have a couple in service, but haven't had them long enough to pass judgement.One last note, if you can hide it or don't mind the visual, put one in the sump and one in the display. This keeps temperature more in line in both areas in the event of a winter time return pump failure.
