I use a combo temp/ humidity it is called acu rite I buy them at Walmart for about $10
For temps I use a temperature gun. The digital thermometers with the probes are OK, but I have found them to be off most of the time. Temp guns instantly read the temp in any spot you want, and are within a degree or 2. Digitals I have noticed can be off as much as 7+ degrees and are usually as much as 3-5 degrees off. I never bought the really expensive ones though, so maybe those are more accurate. There wasn't a need when I could just buy a temp gun.
They are a little more expensive but last a very long time too!