Hawken HE2100. Absolutely love it. The buying experience was absolutely horrible, though. The local dealer is a joke. Makes all kinds of promises he can't keep and has no intentions of keeping. Once Hawken knew about the problem they handled it immediately and continue to call to make sure I am happy with my unit.
Windthrown added a very critical point for OWB's. Stay away from any boiler with stainless in it. A majority of the stainless used for boilers is junk metal and they don't transfer the heat efficiently.
Addressing a couple of the gripes: 1) You will freeze your a$$ off. It's an OWD, first word, outdoor. If you don't like the outdoors, have a propane tank dropped and call it good. Locations that require heat in the winter are cold! However, people buy them because they ARE outside. No insects, dirt, tracking mud in, wood mess, smoke or any of the other undesirables in your home. Garage you say? My garage is often neater and cleaner than the house, I don't want the wood floating around my most valuable possessions. I really like keeping the mess 100'+ from the house. 2) Wood consumption. They do consume a healthy amount of wood. If someone tells you they heat all winter on 6-8 face cords they are either lying or living in Hawaii. I burn almost 8 cords (about 24 face cords) throughout the year in northern Mi (Sept-June) heating all domestic hot water, including running taco pumps to get instant hot water at the other end of the house, the garage, workshop, and 2,000 sq/ft living space (71-72 degrees F). You just have to cut more wood to enjoy the added benefits, small price to pay IMO. 3) Very slow to warm up. My boiler has approx 400 gallons of water to heat to 180 degrees so it takes some time not making an OWB a good fit for a lot of uses including cabins and occasional use homes. 4) Price. Quite pricey with everything necessary to get them up and running, but you get what you pay for. If propane is your other fuel source option it only takes a few years "pay off" the investment. 5) Air pollution/smoke. Somewhat true depending on the type of wood you are burning and the type of boiler. Most companies now make "smokeless" or low smoke chimney's and, of course, recommend you not use them in close proximity to other homes.
I have found mine to be a lot of work, but extremely rewarding. My only regret is not buying one years ago. I bought the Hawken because they are quite prevalent in my area and have a lot of satisfied users. I have found the central boilers to be used with the same satisfaction and durability as my unit. I'm somewhat familiar with the other brands mentioned here, but do not have any real world experience with them. Good luck!