What ever boiler you have, it needs to be part of a system that controls the output, there are a number of ways to control a boiler, switching off/on, connection to ebus, return water temperature, and you have to decide how you want to control it.
Some boilers allow the use of third party thermostats like open therm which can monitor each room and modulate boiler using the ebus, some will only allow you to use there own make of modulating thermostat, which in some cases can only measure the temperature of one room.
Even if your not fitting the controls at same time as boiler, you need to consider what is likely to be fitted. Much depends on the house, my Mold house was open plan and worked great with one single thermostat centre of house on ground floor, my Shotton house however had doors and bay windows and needed a individually control for each room, and my dad had Bosch boiler installed which may have been a good boiler but had no access to ebus which resulted in very limited control.