Standard at 54" long x 20" deep x 34" tall. Are the options confusing? Just take the default if in doubt. Those choices are proven to bring happiness.Often our credenza is ordered in 16" depth because of space considerations (Hallway or Office). Keep in mind the drawer is less usable at those sizes. If you're ok with that we are too.
The Mikel Credenza shows nine layout optionss for the Doors and drawers. Those options will be on the Ostara Page soon as soon as I have time to ad them here, so know they are available.
What is a Credenza? A Case which holds useful things, working things, maybe pleasurable working things. But something we use, not just for meals or entertainment. Usually it has a combination of drawers and drawers, but not always. So a Credenza is only vaguely defined. If you tell me you want a Credenza and it looks more like a Buffet to me I'm not going to miss a beat. We'll call it a Credenza.