Generally, assuming you hire reasonable developers, it is a bad idea to impose a universal code format. It is however a good idea to adopt code guidelines.
I've never seen a set of code formatting rules that optimizes readability in all cases. Likewise there are no 100% applicable grammar rules in English: our brains just aren't wired that way. So use guidelines, but give developers the freedom to override them as they see fit.
That being said, a harder rule of "follow the code convention that already exists in the file/project" is a good one.
But keep in mind that the formatting contributes much less to the readability than simply how logically organized the code is. I've seen plenty of unreadable spaghetti code w/ perfect formatting!