While not necessarily my favorites, and not really examples of McGoohan's more flamboyant style, there are a few lines in the final scene of "Identity Crisis" that strike me as amusing in a more subdued way...
"You have a warrant for everything."
"So I closed the blinds. What's so special about that?"
"You've lost me again, Mr. Columbo."
"This is an office building, I was in it at night, why should not other people be in their offices etc" (what I love about this line is the intense, unrelenting way in which he delivers it; again, not quite as eccentric as many other lines, but still a lot of fun, I think)