My view: A medium long followed by a short is the most painful option..
I am happy to split a trip into equal-ish parts especially if I have lounge access in the middle..
Case in point is that dreaded LAX-ORD after my SYD-LAX.. the 13 hours has broken my soul and the 4 hours on a domestic leg with all the fun of being on a narrow body finishes me off
That said, there are many factors: Good airports, equipment (RJ = no thanks) A direct on a modern widebody trumps two narrow bodies any day (eg 777 vrs 757+757)