The guys I worked with used Delmhorst, but they also used the sliding hammer electrode (another $100) to get a deeper reading.
For the money, I'd go with the Ligno. It's on my wish list.
I have a Ligno and it works great. It is a couple of years old and I believe the newer ones have a digital readout, not the series of lights mine has. Wish I had the newer one too.:dontknow:
Doug