Firefox no doubt, why! i use both on regular basis and i always prefer using FF more... scripts like rutorrent and other phps works alot better on ff and sometimes get stuck or crash on chrome and showed me new flaws evertime. The only downside of mozilla is it takes more memory then any other browser, but an average user have more than 1gb ram which is good enough.
I have seen many programmers and webmasters preferring chrome but most do it for selected reasons.
*Its a google product so who doesnt want to (its like iphone users who just wants to go with the goodwill of the name)
*Its lighter
*It looks cooler
Whether its about programming, faster browsing, modifying it to the way you want Firefox is still way ahead of any other browser. Even the simplest thing like copy pasting is so much user friendly on it.
I do like chrome alot too and the way it has progressed, im sure it will become a benchmark very soon !