Hi John..... I can't say which is best as I'm not familiar with the PitmasterIQ. I am familiar with the DigiQ however. I've had one for several years and love it. Mine is the DigiQ DX2. I see there is a DX3 available now and I'm not sure what upgrades they've made. Very easy to use and accurate. I did however upgrade to the CyberQ Cloud a couple of years ago and that is my favorite, mainly because I love being able to keep and eye on my cook using my IPhone and make adjustments if necessary, regardless of where you are. A bit more of a learning curve with this unit, however their on line support is outstanding and will assist with the setup if necessary.
Made by the same company who makes the DigiQ is a budget conscious PartyQ which I have and love. It's a no frills ATC that I really like. I've read alot of good reviews about the DigiQ as well but I went for the PartyQ for the $$.