Sentinel is hands down the best. This is a great indoor/greenhouse unit. Co2 is a plus but watch out cause you can dump alot without a ppm meter. I run the new sentinel chhc-4i for my room that needs co2. I use the evc-2 for plants that don't need precise co2 levels. I turn the co2 regulator on the lowest setting and let the evc-2 spray during the day when my cooling fans are off. I use this unit with 2 6" inline fans on the temperature plugs (there are 2 plug ins). I have a dehumidifier on the humidity plug. I have a oil tank style heater on the night device plug. And of course a co2 regulator relay plugged into the co2 port. Keeps my greenhouse temps perfect and allows me to run seperate night and day temps. But also allows me to not have my greenhouse freeze at night. What else can I say. If you don't need to run precise co2 levels on fuzzy logic buy the evc-2. If you want fuzzy logic the new unit I mentioned above is perfect. Actually I ran the two next to each other my new sentinel chhc-4i and this older evc-2. Temps were within 1 degree of each other. Humidity was within 3 percent of each other. I wanted to make sure the used evc2 was working before I trusted plants to it.