I have the long stem dial thermometer for putting in the mash or monitoring temperature as I bring the wort to a boil so I know when to slow down the heat to avoid boil-over. I also have an infrared thermometer that I use to monitor the fermenter temperature. I tried the stick on ones but I couldn't read them in the darker room where I was fermenting. With the infrared, I just point and shoot.
While I love my infrared for what I use it I wouldn't use it for mashing because it might be reading the temperature of the steam instead of the mash and the surface of the mash won't be the same as the middle anyway.