In the dehydrating world, the Excalibur line of dehydrators are considered top of the line for home dehydration. If you're going to be doing a lot of dehydrating, I highly recommend them. The problem with a lot of the stackable round ones is that A)they don't have a thermostat, and B)they don't have a fan to circulate the warm air. It takes much longer for things to dry, you have to regularly rotate the trays, and I lost almost half of whatever I was drying to mold growth.
An Excalibur is enclosed (with a door that is separate from the tray fronts, allowing you to use as many or as few trays as you wish), has up to 9 trays, varies in temp from 95 deg (for people who are doing "raw" food drying & want to keep the nutrients in it) all the way to 155, the desired temperature for meat. I can also proof bread & make yogurt in my Excalibur. They are expensive, but they almost always have refurbished ones on their website that are like new, with a 10 yr full replacement warranty.
I have been incredibly happy with mine, and wouldn't trade it for anything, especially now that I plan on making all my backpacking meals with it.