Paul,
Just my 2 cents..
More than everything else, the grafting success depends on your skill. That includes your technique, how well you graft, timing of the graft (during the day and the year), how well you protect it from the sun and moisture, quality of the scions and rootstock.
If you master the grafting, I would say that would give you a higher success rate, but for a person who has never done it before, I would say the rooting is preferable.
On the other hand, if you have a lot of cuttings, grafting them all may not be possible.
Also, do not exclude the beginners luck :)