I would have to say for me a Thermapen. I dont cook very often with wired (although I think that is a really good way to cook) I have sort of an idea with time and temp so the thermapen is it...second is probably Grill Grates.
I would have to say it's my Maverick remote thermometer.
I love being able to hot-smoke bacon, sausage, etc. on the MAK which can take hours to slowly get up to temp. I can set the alarms on the maverick and go do whatever else I need to do and know that the alarm will let me know when it's time for the meat to come off. I can even go to bed if it's late and the alarm will wake me up.
Great question. I also us a Thermopen and at times my Maverick but almost every cook I use those cheap aluminum foil pans (in various sizes from WalMart) to carry the food from the house to the cooker. With the pan and a good pair of heat resistant gloves I'm good to cook just about anything.
Right now, after years of stick burning, the whole MAK 2 pellet grill/smoker is a gadget to me! Tinkering with cooking methods, smoking cheese, different pellets, etc. -- the possibilities are seemingly endless.
I am also having a lot of fun with the "virtual" gadget known as MAK Grills Mobile...
Believe it or not...my "go to" gadget is the ThermoWorks "Extra Big and Loud" waterproof countdown timer... I use them to keep me on track at comps during crunch time, and at home when grilling, smoking, cooking, or baking. Right behind that is the ThermaPen...
Certainly the Thermapen. If I could only have one, that would be it. Luckily I can have more. Maverick for my drum, GrillGrates for my MAK, AmazinSmoker Tube. Hopefully a Vortex for the drum soon (BP?). ;-)
The thermal pens gets used all the time. I give them as gifts! We have MAK grills that have three temp probes and two stokers that we could use unlimited temp probes on. Yet 95% of the time we cook a certain time and temp and check with the thermapen to check temp and either take off or cook a little longer. Do love the grill grates which we use upside down for fish a lot . Big Poppa Mats live on our MAK grills. Which we don't clean just bend and shake and ready to use again.