If you don't have a set pattern of travel, then it becomes difficult to choose a UY that gives you the advantage of planning travel during the timeframe when your points are able to be banked. We are kind of that way, in that we have travelled every month except Sept and Nov. Going forward, we will probably travel mostly in the summer, as we have a school age child, but occasionally Oct or Dec. We have a Dec UY, which is really only good for those summer and Dec trips.
When you can't choose a UY that works best for you because your year-to-year travel schedule is erratic,
then you may want to choose a UY that is in abundance in the resale market, if you ever see yourself purchasing additional points after your initial purchase. Here is a link to a site that shows the distribution of points by UY for each resort:
http://dvcnews.com/index.php/dvc-program/owning-dvc/2014-updated-points-distribution-by-use-year
I would probably be inclined to avoid buying a contract with less than 10% of the points in that UY month, simply because it may be difficult to find add-ons in the future with that UY. If you don't see yourself ever buying another contract after your first purchase, then it probably does not matter.
Good luck hunting for that perfect contract!