For most (?) folks it's convenient to place the home hub / router next to - or near the ONT (they and the cables are often 'dumped' in a cupboard and forgotten...
I want to place the ONT where I have the existing NTE5 and base telephone are. A Cat6 cable will then run to the router and a gigabit switch for all the rest of our boxes are.
The perceived wisdom is to keep the ONT and router together - but I can't see a technical reason for that.
Have I missed an important point?
Your router does not need to be beside the ONT, it is connected to the ONT by an ethernet cable, any reasoonable distance will be fine.
It is important to place the router in a location to give good wifi coverage.
As long as the ONT and router are no more than 100 metres apart (the distance limit for Ethernet) there is no problem.
If 100mtrs is a challenge then an ethernet bridge would solve it.