I don't agree with the notion that a "mom and pop" shop gives you better service than any other company, a loan officer is the one who provides the service, the level of that service is often impacted by how busy they are and how much help they have. I know plenty of LO's at "mom and pop" shops who are too busy to answer the phone working on refis let alone talk to a new customer or first time buyer who may have a lot of questions, the same applies for LO's at other bigger companies.
The service will depend on the LO, not the company they work for. There are certain things that are outside of the LO's direct control, this will be a function of the company they work for or the vendor they use, these are things you may or may not have an issue with.
Some LO's will make the time somehow, even if that means less free/family time, others will hire assistants (if they're allowed/financially able to), etc.
As for rates, I have friends in many, many companies locally here and elsewhere, we all have very similar rates, some have better pricing in certain products than others but overall everyone left is fairly competitive. You won't be able to call a company and get quoted a 3% and the next guy tell you 4% on the same loan scenario, those days are over.