I voted Ardbeg 10. To me it captures everything just right. The others I've tried:
Ardbeg Uigeadail: very good job putting this one together, but I find it just a little rough around the edges.
Laphroaig 10: good bargain for a standard strength.
Laphroaig 10 C/S: more punch than a heavyweight boxer, great.
Lagavulin 12 C/S: a little too hot for what it tries to be, but cut with water(which I rarely do) it really finds its place.
Lagavulin 16: Love its unique quality and richness. I save it for special occasions.
Laphroaig 15: yes it really does belong in the poll, but I would love to find a Laphroaig at this age as a C/S, I imagine that would be sublime.
Ardbeg 17 is not "Heavily peated" so would not fit here, although very good.
Also, it is hard for me not to include Highland Park, Talisker, Caol Ila and a couple others if someone is looking at this for the smoky, peatiness and not just South Islay malts.
Looking back over my comments I realize I may have come off as critical. Let me make it clear that all of the above are GREAT bottles and worthy of at least a try and I highly recommend them all. It's hard to critisize something when it's all good.