blessed2BaMama makes some good points. Point number 1 is probably the most important issue when choosing a UY. Point number two is perhaps a consideration if you plan on building your
DVC ownership over time, but you may not be able to avoid the low availability UY if you find a contract and UY that meets you needs. DVCNews.com has the
point distribution by UY charts, if you want to look at that in more detail.
In reality, most people cannot predict when they may be traveling over the 30-40+ years left on the contracts, so it may not be an issue for some. We initially started by going to WDW off season (Oct, Dec, Feb, Mar), but now that DS7 is in school, we are more on the school calendar (Spring Break, June-early Aug). Our UY is Dec, so we have to bank by the end of July. That still works for us, since we could cancel a trip that is scheduled in July and still be able to bank the points before the end of July.
The banking deadline for each UY is 8 months from the start of the UY. So Dec UY banks by July 31, August UY by Mar 31, Apr UY by Nov 30, etc. Ideally you would like a UY that has your usual travel dates in those first 8 months, so if you do have to cancel something at the last minute, you are still in you window for banking the points into the next UY. Here is a
thread about use year.
Happy hunting!!