I knew thee were many choices pertaining to OWBs, but like muffin stated, there are no set standards to go by and no way to really do a contrast scan, and of course everyone will tell you their furnace and company is the best on the market.
I did as much research as I could possibly do and after a while they all began to look the same...except in price. I planned to install the furnace myself so I was looking for the least expensive, yet quality furnace. I know most of you sitting at home reading this are going to choke on your coffee/beer /"insert choice of drink here," but I chose a Shaver 250. I liked the fact that they have been in business for quite a few years and that their furnaces were pretty much basic. That if anything went bad in them, outside of the water jacket...that i could go to Fleet Farm or Menard's and purchase whatever it is that I required.
I had an installer form Central Boiler, from about 15 miles down the road come out and give me a price for the entire installation and furnace...well golly gee whiz I would have to live in the house for 60 years to recoup the total investment Price: $15-17k. then I checked with another company just outside of Green Bay,WI. and they too said it would cost me about $14,990.00 for the entire installation and furnace and to this day I don't recall the name of the furnace.
I decided to install everything myself or at least part of it and barter out the rest and I went with Shaver. If I figure correctly, I can recoup my entire initial lay out of money in 5-6 years. This is really quite good compared to 50-60 for anyone else. Is the Shaver perfect? By all means no, but the price was right and this is all that matters to me. It burns wood and heats my house and hot water heater. Next year it will heat my shop.