The original Arkanoid is it for me, I still remember the first time I saw the arcade machine.
Other one I loved was Crack http://hol.abime.net/3108
in it's 80's rainbow copper glory.
Later on I played a lot of Poing during downloads.. ;-)
Still, I voted Arkanoid. Not the flashiest but it was "the original" for me, even though it itself was a clone.