The mortise and tenon joint could probably be considered the cornerstone of furniture making. The dovetail is certainly prettier, but not nearly as common or helpful. I can make tables, chairs, and lots of other pieces and never even think about a dovetail.
My preference for making a mortise and tenon joint is to use loose tenons. I find them much easier and quicker to create, and the shoulders are always coplanar. You have to make at least one mortise anyway; why not make two while your at it? Then make the tenon using your planer, allowing you to sneak up on the fit.
I didn’t come to this decision without a lot of head-scratching. I made lots of M&T’s before getting here, and have taught lots of students how to make them. My thoughts on some other methods:
Mortise: Hand chopped – Neanderthals only. Drill press mortise, cleaned up with a chisel – too much work, but the simplest method in terms of machinery used (unless you don’t have a drill press). Router jig mortise – not a bad choice if you have a decent jig, and a decent jig isn’t hard to make. Hollow chisel mortiser – I have always had a philosophical objection to the “cutting” action of this tool, although I know they work well with a sharp chisel and bit. Slot mortiser – the best method, but you have to own a slot mortiser, and the simplest ones are over $600. Dedicated joinery machine (Leigh FMT, WoodRat, etc.) – not a bad way to go, but can be complex and pricey.
Tenon: By hand – see previous paragraph. Table saw/dado set/sled – works okay, but I don’t like the surface left behind by the dado set. Table saw/tenon jig – works well, but multiple setups involved (although this is my second choice). Slot mortiser – difficult to set up most of them to do this well. Dedicated joinery machine – see previous paragraph.
And, let’s not forget about the square-end/round-end mortise/tenon issue. I don’t typically make through mortises for Arts and Crafts style furniture, so this isn’t an issue for me. Round-ended tenons work just fine; no one sees them anyway (not that I’m trying to hide anything…)
All that to say I like loose tenons. Which means I own a slot mortiser. Can’t do loose tenons easily without it. Mine is an old Inca machine, originally intended to mount on the back side of an Inca model 259 (I think) tilting-table table saw. That little saw was rock steady, with arbor bearings bigger than my Powermatic 66. The problem with the mortiser attachment was the bit speed; it ran at the same speed as the saw blade, about 3400 rpm. Very slow by router bit standards. I purchased the trick Clico bits, which were supposed to work well at that speed, but the whole process was too slow…
Until I built a new jig around the mortiser that allowed me to use my router:
This thing rocks! It cuts mortises accurately, quickly. and cleanly. Messy and loud, but I can live with that. I made the fixture of MDF, thinking it was a prototype and I’d make the “real thing” once I got the bugs worked out of it. That was about six years ago…