How big of a tank are you keeping your ADF in? I used to have the Hydor Mini Heater, and it really overheated my 2.5 gallon tanks. Other people have had more luck, so you never know. A problem with both of these heaters is that they just heat the ambient temperature several degrees, so if your room temperature is normally chilly or ever fluctuates at all, they would not be good options. I haven't used the Zoo Med Heater, but the fact that it heats ambient temperature 5-10 degrees is a little unsettling, that's a huge range.
If possible (and depending on tank size) I would go with an adjustable heater. When I first started with fish I tried basically every automatic heater out there and they either didn't work at all, or they overheated the tank. I thought I was saving money by getting inexpensive heaters, but I was really just wasting it on multiple heaters that didn't work properly. Now I only use adjustable heaters. I have an adjustable Marineland in one 2.5 gallon tank and an adjustable Hagan Mini heater in my other 2.5 gallon tank. They have both been very reliable.
And that Hagen from Allpet is a great price! Even cheaper than the Hydor Mini!