I have a couple of Burnham boilers, a hydrotherm boiler and a Hamilton Boiler (Lochinvar)
The Hamilton boiler is my favorite
Also look at Weil-McLane boilers.
Look for a sealed combustion chamber, stainless steel burn tubes, you want to get efficiency up over 90pct, but that comes at a price.
Also multiple stages within the boiler. On the small ones that might not be possible
One other thing, make sure the boiler installers place shut off valves on both sides of all your pumps, i.e. cicrculator loop pump and zone pump(s). When those pumps need servicing, the service work is neater and easier when you can close off the boiler on each side of the pumps.
Point of use works well, but its expensive, especially if you go with a sealed combustion system and draw air from the outside. We just replace our old water heater, the cost for the water heater with a sealed system was $1100 vs $1900 for a point of use system with outside air for combustion.
Joe