>Never watched the anime though. Is it better than K-ON ?
I wouldn't say either is better or worse - if you like one, you'll probably like the other. However, K-On is more "grounded in reality" while Lucky Star gets quite zany at times (vid related) and relies more on references to other shows/media & otaku culture

Just a warning: the first Lucky Star episode starts off with a mundane conversation about food that seems to drag on forever, but it does pick up and get better from there. It's similar to Azumanga Daioh in that regard, which also had a pretty lackluster first episode