The title tag is. But that doesn't make it the most important factor for SEO. That's an important distinction.

I agree - the title tag.

Yes, me too agree! Title tag is the most important tag for SE's!

Use of keywords in title tag would help in SEO. But don't over do this otherwise you may get ban..

You won't get banned for stuffing keywords in your title tag or anywhere for that matter.

You just won't rank for much because every keyword would be too diluted.

Yep. It's not smart, but it won't get you banned.

I vote title tag as well. A well formed title tag will help you in Search Engines, especially Yahoo and MSN, plus it will be enticing for users to click on once they find you in the SERPs.

I agree title tag and the point made above about is very true, if your title is something that someone is looking for then that will bring them straight to your site. That has only happened to me a few times where I have searched for something and it has come up in the exact same words in someones title. Of course I clicked on it instantly.