In The Canterbury Tales, which pilgrim is described as an epicurean, a person who lives for pleasure?

You could probably make a case for many of these characters to fit that description, but the main guy you're looking for is the Franklin. The Franklin is said to be a man who loves the finest food and drink and is never short on either. In my translation, you would be most interested in lines 345-348:

"He lived for pleasure and had always done,

For he was Epicurus' very son,

In whose opinion sensual delight

Was the one true felicity in sight."