This thread still lives on? XD
I would vote for Naruto because I really don't know the anime LuckyStar. Never watched it. But Naruto. Watch it always!
Which shows the main fault this thread presents. Naruto and Lucky Star are too different for such a comparison.
Naruto is a long-running mainstream anime that pretty much anyone who even knows what anime is has heard of. It is an anime of action that pulls in boys who like action involving ninjas and flashy shows of strength, and girls who, along with liking such action, love it much more when boys like Sasuke are in the picture. Naruto appeals to everyone in some way, bringing in the most attention.
Lucky Star, on the other hand, is a 24-episode anime (which ended its first run just a couple months ago) that mainly pulled in the more hardcore (by that, I mean those who watch more than mainstream) anime fans with the non-existent plot coupled with light-hearted comedy, and references to Japanese culture and other anime. Lucky Star, therefore, is harder for the casual anime fan to follow along with, making it an anime you can't get into without knowing what to expect of it first.
I believe the only reason this thread was made was because Lucky Star was widespread awesome at the time, but it is done now. And while those of us who do love Lucky Star are waiting for the hopeful second season to start soon, Naruto continues to run strong.
Me? Naruto isn't my thing. Just never appealed to me. But I can understand well enough why Lucky Star wouldn't appeal to most. Still, some people (Edit: no one in particular, although a few of my cousins who live on nothing but Naruto come to mind >.>) would do well to at least give other anime a try.
I will now end this post with an animation that I haven't gotten a chance to use in a while. =D