I started with the Wyeast mead yeasts and even the sweet mead yeast produced a dry 14.5% mead, it has to age a couple of years to be really good. Back in college I was given some Vierka yeast. I have not found too much info on it but one reference said it was an "old timey" mead yeast, one of the few available back before mead became popular again and it has fallen out of common use. I had a hard time finding it again but finally bought some. I have had great luck with it. My BIL compared Vierka, D47, and EC1118. The Vierka was the best overall. In our monthly tastings the D47 had one point (two months in if I recall?) where it was better than the Vierka but then the Vierka mead passed it up - but both were close, good tasting and good quality meads. EC1118 came in last at all points in this experiment. I can't really describe the tastes like a judge can, we just tasted the meads and made comments such as: "I like this," "This is smoother," "This is 'rough'," etc. Of course this is all subjective and everybody's tastes are different.
If Vierka becomes unavailable and I loose my culture, I will switch to D47.
I'm experimenting with DV10 right now, it produces a crisp clean mead without very much yeast influence to the flavor. Great for the OB hydromels I have on tap but I prefer Vierka for regular meads.