Thanks for your answers !
My current issue is that I'm not 100% sure of what will be the purchased camera.
A friend of mine, with extensive photographic experience, told me Sinar was the best for him, but I'd be tempted to look for an Arca. As Arca has bigger boards than Sinar, it would seem reasonable to make a 140X140 board ?
What is the Linhof board standard ?