I used to have only Helix, then I tried the Herpstat pro and fell in love. Since then, I switched everything to Herpstat.

Helix was good for one or two racks, but only has one temp probe. With the Pro, I have 4 probes and plug-ins for 4 separate racks. Everything can be tweaked, and I can do night drops without having to buy an extra piece of equipment.

Haven't tried the others on the list.