I am a hobbyist and do own a Domino, a biscuit joiner, and a Kreg jig.
I never used biscuits much and, when I did, I usually found that it was difficult line up the parts, especially when gluing edge to edge for a wider board.
I used pocket holes quite a bit for drawers and cabinets in my shop. They are easy, strong, but it is also difficult to keep the parts from moving just that a tiny bit. It's annoying and, to me, degrades the quality of my work.
The Domino, however, recently changed my entire way of thinking. I made a nightstand and used nothing but Dominos for the joints which otherwise would have been true mortise and tenon joints. This included some Dominos plunged in the middle of the underside of a bottom shelf that permitted the shelf to appear suspended above the support underneath. These joints were fast, extremely accurate, and very strong; I feel as strong as true mortise and tenon joints. In fact, I would suggest that, for me, the Domino joints may be stronger than my mortise and tenons on other projects because the Dominos fit more tightly than my other joints and, therefore, yield a much stronger glue joint. Plus, when you do the glue up, the result is a perfectly square joint in such projects as drawer boxes.
The Domino would be my choice for almost any project. I generally use a few Dominos even when just gluing up a top or shelf. By referencing the same face on each board, the top is virtually perfect and requires almost no sanding to get rid of the glue line ridge (if any exists). I have the time and, while the Dominos may take slightly longer than a pocket hole, the result is better.
