I voted Ardbeg, because Ardbeg 10Y made me a single-malt lover, and I promised to never forget. But in fact it's not so simple to answer the question which is my favourite Islay malt.
It's all a matter of price/quality balance. I like the bowmore seadragon 30Y (USD 350,00 a bottle these days) more than the Ardbeg 10Y...... Bowmore is my favourite brand because they have a lot of good malts to choose from. The Bowmore 17 Y is one of my all time classics, complex , fruity and balanced, with some peat, but not medicinal like some other (younger) Islay whisky's.
In fact I like all Islay whisky brands. Even the one's with less peat like bunnahabhain and some bruichladdies
Even Lagavullin is not so bad
I heard some rumours about a possible takeover of Laphroaig by some big company like for instance diageo. I have a small advice for them. Keep your filthy hands off Laphroaig!! If you want to buy an Islay distillery, buy Port Ellen and give us back Port Ellen as a working distillery. Love Port ellen