A class B will normally cost more than the others - will your budget meet those?
The class A and class B will feel different driving - go take a test drive in both and see how you feel with each.
Go to a dealership and look at the floorplans that meet your requirements. Spend time in them acting out making meals, getting ready in the morning, etc. Imagine the dogs at your feet while you do these things. If one feels awkward or tight, cross that Floorplan on the list. Then when you have the floorplans that you like, go to the Internet and look at different makes and models with those floorplans, read reviews on them, look for complaints, etc.
Take your time and do a lot of footwork.
