I'm also a Quark fan. It's a very juicy part for an amazing actor, and I think he succeeded almost single-handedly in making the Ferengi believable.
Of course they're comical but when I look at Quark, that's not all there is to him. Armin Shimerman gives the character a substance that makes him real. He has his serious moments, he has his deeply felt emotions - occasionally even about things other than latinum - he even has the odd attack of uncharacteristic valour and I can buy them all. The actors who play his brother and nephew did sterling work as well.