Whip finish by hand. Everything and everysize. If you are having trouble bending the hook on smaller flies use less pressure on your wraps, the thread is not going anywhere. Personally I use head cement, the runny stuff, either applied with a bodkin oy a cut quill tip the latter for precision for un waxed thread and store bought waxed thread. I tie a lot of my Flymphs using wax from an old recipe from J Harrington Keene that Leisenring favored. This wax is basically an adhesive made mostly of pine rosin. Tie a fly with this stuff and the fly is virtually indestructable including the whip finish at the end. The half hitch is the least secure and reliable way to finish a fly, head cement or glue is a must or your fly will unravel. I'm not a big fan of the wonder glue. I've had flies unravel using the stuff. Went back to the bench and tried use the glue in conjuction with a whip finish and had a glob at the end of my fly Head cement is just easier for me.
Great question.
Jim