A good question which is worthy of starting a bar fight. :icon_smile:
I have an inexpensive General Instruments MMD4E meter, which is the pin type.
I do not notice the dents from the pins. This meter works well enough for my needs.
I purchased mine from Lowes. The site is messed up, description say temperature meter, but it is a moisture meter.
http://www.lowes.com/pd_78059-56005-MMD4E_0__
Prior to getting this meter, I had not appreciated how much the moisture content varies around the surface of a piece and within the piece. The only time I check the inside if when I have rough turned a green bowl.
With so much variation is it hard to determine the "average" moisture content of a piece. Hence I am not sure of the value of a more expensive meter which may be a tad more accurate - since the wood can be so varied.