WL 530/WY 3787 is my favorite for Trappist/Abby styles.
WL 565/WY 3724 is my favorite for saisons. I accidentally bought 3726 for my last batch, and it was not as good.
WL 515 is a great strain from White labs that doesn't get much attention. It makes a nice pale ale that is clean and slightly lager like. I would say it makes a nice Fat Tire kind of beer, but I don't like Fat Tire. Use it for a Fat Tire clone, but use good Continental pils malt for base malt, some Munich, Cara-Vienne, and Biscuit for specialty malts and saaz for the hops.