I selected the Earthstone about 9 years ago when there were fewer alternatives. IIRC, Earthstone and Mugnaini were the only ones I considered. I am crazy about my oven, but I don't really have any basis of comparison. If I were starting over today, I would include on my list the oven sold by marco and the one built by pftaylor, depending on your requirements and budget.
The efficiency and cost of cooking with wood has a lot to do with how much thermal mass you are trying to heat and how much is lost during the firing and baking. This may have more to do with your particular installation and construction than the basic components sold by the manufacturer. FWIW, I over-built my with more mass and insulation than called for by the manufacturer. As a result, it takes more fuel to bring up to temp, but stays hot longer. So it is less efficient and more expensive to operate if you are baking a small number of batches, but more efficient and less expensive for larger batches. I try to maximize efficiency by cooking multiple meals (breads, roasts, etc.) from a single firing.