My California based credit union doesn't even offer business accounts. And using the co-op network to do in-branch business at other credit unions is not as easy as the marketing lead me to believe, so I had to get a local credit union account where I moved as well. My Washington credit union does do business accounts, so that's a nice option if I need one. Plus, it's fun being a member of two aerospace/defense employee credit unions when I only worked in tech :P
On the contrary, a highly concentrated bank might be better, everyone is on the same building, there are no encapsulated branches, you get assigned a banker that is the best fit, rather than the one who was born closest to you.
When the bank has many branches, there will always be some steps that require visiting the main branch, and the opening branch.
With a single branch bank, the main branch and the opening branch are one and the same. And it's the best branch.