If they offer "paint grade" that is fine and saves money- it is typically Maple but lesser grade but can be poplar in rare cases (softer) yes WM/BH paint is different, not convinced it is that different or any better- harder to touch up though.

MDF center panels with maple stiles and rails is the preferred choice for painted cabinets. It will minimize the wood movement and paint cracking. Lower end "custom" guys will use plain house paint, but your better quality manufacturers will use higher quality materials that the local maker cannot get access to.

Thank you both! Holly, is the MDF center panel preferred for catalyzed factory finish as well? I was thinking MDF was a lesser quality than a solid wood. Are you saying that all solid wood would cause a problem with natural expansion and contraction?

Thanks

I'm saving money by choosing mdf panels for my painted white shaker doors. My custom cabinet builder advised that it will have less expansion/contraction cracking - but also that the sound of doors closing is less "solid".