Both of these methods can be used, and both have their flaws. Neither will recreate completely accurate results, although both of them can get you close.
If tuning for only one frequency the 180 degree cable will get you more accurate results when it comes to X (resonance) for said frequency. However, in the real world, getting a 180 degree cable tuned perfectly for the frequency in question isn't really that easy, it will pretty much always be off to some extent. Due to losses in the coax, this method will also throw off the R reading as well. If you are one of those that thinks resonance is always the best to tune for this method is for you. This method is less accurate the further away from the feed line's tuned frequency, and those inaccuracies add up faster than you might think (at an exponential rate).
On the other hand, if you are tuning for a range of frequencies, the very short jumper method is more accurate. While not providing as accurate results as a well trimmed 180 degree cable for measuring resonance on a single frequency, it's accuracy is much more consistent over a wide range of frequencies. Further, you can control how far off your readings are, at least to some extent, with the length of said coax.
If you are a "perfect SWR match" tuner (that is readings of X=0 and R=50 on the analyzer), then in both cases the closer you get the antenna tuned to that point you are looking for the more accurate both of these methods are going to be, so either can be used equally well by you.
The DB