If you're writing code which only needs to run in R2014b or later, then the first form (aka "dot notation") is preferred. There are a couple of reasons for this.
- It is faster.
- Tab completion is a bit more robust when you're using it.
- It also makes your code easier to read.
There are two caveats (aren't there always?). It currently doesn't work for arrays of graphics objects or with functions which return graphics objects. So these two cases don't yet work.
h = plot(magic(6))
h.LineWidth = 6
gca.XLim = [10 20]
You should continue to use "set" for these two cases, although I will usually write the second like so:
ax = gca
ax.XLim = [10 20]
And, of course, if your code needs to run in earlier versions, you should use "set".
