Hmm...
My favorite would be "RRROARING FIRES! MALT BEEERR! RRRED MEAT OFF THE BONE!"
Others I greatly enjoy and perhaps quote too often:
"Oh, Sam!" / "Sam, I'm glad YOU'RE here with me"
"You cannot wield it."
"BILLLLboooo Bagginssss!"
"It comes in pints??"
"A great eye... lidless... wrrreathed in flames..."
"I ain't been droppin' no eaves, sir, honest"
"HAAAGHHH!" (Bilbo's eye googlies)
"...and they call it a mine... A MIIINE." (then, for some reason, in my Templeton the Rat voice): "This is no mine, it's a tomb"