I like Belgians more on the subdued side so which Belgian yeast would have the least phenolic and esters. the new one from Wyeast sounds interesting Wyeast 1581
I just used antwerp ale from white labs. Its a seasonal but as described fermented pretty clean (for a belgian anyhow) and accentuated the malt quite a bit in the batch I just made. I didn't even ferment all that cold I think it got up to 72 at some point. I agree the belgian stout strain sounds very interesting.
Yup, ferment it cool and it will be quite mellow with the phenos! I bought a Farmhouse Ale yeast with the intent to enter in a contest, the entry did not happen before I brewed so I brewed and fermented at 64°F and it turned out pretty good. I entered a different contest as a Saison and scored 35! (the comments were that it would have been more to style if it were fermented warmer as it lacked the esters the style called for)
That has been my experience with WLP550. I fermented a beer @ 64 and it was crazy phenolic, almost undrinkable. It did mellow out after a few months but was never that good. On my second attempt with that yeast, I pitched at 65, held at 68 for a few days, then ramped up one degree a day up to 75. The results were much better. No detectable phenolic character, at least to my palate.
Brew Like a Monk has some great info on this topic in chapter 8. For Wyeast, your best bet is 3522, it's 510 for White Labs. Do a cooler fermentation for both of them, ~65F.
I've found Wyeast's 1762 to be the most "neutral" of the lineup, though I haven't tried them all. Fermented cool, around 65-68 tops, it's mild, but definitely tasty.