Building custom cabinets is one of my favorite carpentry related endeavors. I have been building and installing custom cabinets for customers for over a decade. In the beginning, the cabinets that I built were simple, cost effective and usually site-built. I was limited insofar as my shop was essentially my van and the tools within. I was installing factory built cabinets from mainly Wellborn and Kraftmaid quite a bit back then and most of the custom jobs were small vanities, laundry cabinets or bookcases that the customer wanted (usually as an afterthought) in addition to their kitchen remodel. Since then, I have acquired more of the tools necessary to build larger, more complex cabinetry and have an off site location to build and finish them. A quality factory built cabinet is still an excellent choice for a kitchen remodel, especially if cost is a concern, but design options may be limited. The fit and finish of factory built cabinet face frames, doors and drawers are usually excellent. Quite often, only the top of the line cabinets coming out of factories have carcasses (boxes) made out of plywood; usually they are made out of thinly veneered particle board, which has a tendency to absorb moisture and swell and are not recommended for use beneath granite, stone, or concrete countertops.
Whenever I build a custom cabinet, I usually use pocket hole joinery and glue for the
face frames and the carcasses (with shallow dado cuts to keep everything aligned)and pocket hole joinery without glue to attach the face frames to the carcass. Panel doors, either raised or recessed are joined with mortices and tenons shaped as a profile into the door frames. Drawer boxes are glued and joined by recessed screws which are plugged, or they are glued and rabbeted and staples are used to hold them together. I try to use solid wood for drawer boxes and will
usually default to poplar as the material of choice, but it can be any material the customer wishes, from cheap plywood to wood that matches the face of the cabinets.