Viessman boilers are top of the line, and most will say if you can afford it, go for it. That being said, the other two are very good too, with people in the biz saying SS boilers have less problems and will last longer. My suggestion is if you are renovating, which I am doing now as well, is to make sure a heat loss calc is peformed. You will most likely be upgrading windows, insulation etc. and I guarantee you will get a smaller boiler than you have today. Unless of course you are doubling the size of your house. In my case, i am on my 2nd addition, nearly doubling the size, and the boiler is 1/2 the size of the original.

Bakerboy63, thanks for the response! The Viessmann sound really great, and I do like the idea of stainless steel. On the flip side, the Buderus seems like a good middle ground between Viessmann (more obscure) and Burnham (hear mixed reviews about warranty/customer service.) The thing holding me back from Buderus is the aluminum material. I also really appreciate the input on calculating heat loss. A good contractor is clearly key! Thanks again!

While I prefer SS, that Buderus AL unit is good. The key with any of these, AL or SS, is to do a thorough and complete system cleaning flush using the manuf recommended brand of cleaner, prior to start-up. Fernox or Hydro-Solv may be the right ones. Once everything is cleaned up and you have good water or AL safe glycol...and you check it within the service schedule, that Buderus is excellent. I'm assuming the specified V is the 200 and not the 100. They are different and you want the 200. I would avoid the Burnham. They are an old line US manuf, but they seem to keep making boilers that won't hold water over time.

newenglandsara, so 5 years later, what did you go with and how's your experience with that boiler been? Also how was the install process, etc?

Rob Lyons, we went with Viessman, and it has been terrific. The only regret I have is that I did not service it regularly, and now we need to do some maintenance. Hope this helps!