I fit Broags all the time. Very good boilers.
Parts are no problem. The merchant who supplies them will have a 'first aid kit' of spares that the installer can pick up foc to fix the boiler first time.
Veissman, I have never fitted, but worked on some. Don't like them, aftersales can be hit and miss depending what area you live.
Vaillant good, but atrocious after sales service.
Ideal, forget them, unless you are glutten for punishment.
Worcester, ok but a nightmare to work on, excellent after sales service, but one has to ask how we all know that
There, and I said I wouldn't reply