...assuming you believe there is such a thing as a great comic strip, and assuming this subject hasn't been done to death, before.
My own favorite would be Krazy Kat. If you haven't ever seen it, look for collections in places like Amazon.com. It ran from 1919-1945, I think, and is one helluva of zany strip that mixes knockabout humor, wild, erudite language, surrealism and philosophy. It had an enormous influence on another strip I really liked, Bloom County. (In fact, Breathed deliberately paid hommage several times to Krazy Kat by using the format of a continuous conversation held over ever-changing, wierd backgrounds, with the protagonists floating in midair, diving, standing, etc.)
And yours...?