From left to right, Millers Falls, Boss Double Eagle, Ajax, Snell.
Each machine has it's own unique features. I like the Millers Falls the best. The Boss has a double chuck with different gear ratios. The Ajax has a special chuck that allowes the use of old T-auger bits and a angled depth stop that shifts the retraction mechanism into gear when the proper depth has been reached. The Snell is a basic no frills economy design. Tom