Using Firefox after years of Explorer, is like walking without the ball and the chain. Since W7 one is really free.
I would say if you are using it to purchase (i.e. gotta enter the CC number etc.) then use incognito mode in chrome, private browsing in firefox or InPrivate Browsing in IE 9. All these browsers are fine but chrome is the best nonetheless.
Best Browser There is no overall champion IMHO, just whatever suits your needs! Opera suits my needs with its built in email client and speed, but, its development went backwards with the introduction of the plugin wrapper as it causes considerable problems to date. Not only that, it needs to wear a mask on certain websites as it sometimes gets rejected for daring to be different. I like Chrome, but its present inability to interface with Outlook 2013 renders it unsuitable for my needs, but, it is very fast and easy to personalize and seems to be as secure as any competitor. Firefox and IE I never liked, even to the present day, but many people do, so my personal dislike can be ignored as it's pretty much subjective. Safari 5 was a browser I liked using, it had nice styling and was pretty fast, unfortunately it was insecure from day one. Anyhow, Safari 6 is not Windows compatible, which is a shame, a lot of political games being played at Apple, methinks a new world order is being pursued.
I use Chrome with single problems! At the moment V. 26 Final and it's faster than any other browser I checked.
Any top 3 browser should be fine, the browser itself is worthless without proper security in your system as well. Hope you do not plan to rely on just a browser to protect your credit card e.g. if you are already screwed by a virus and use any browser with a credit card, you are at a loss already.
I'm using Firefox at the moment. However, i'm also checking what will become of Opera since they are rebuilding it from ground up. IE 10 is ok too but because of the addons i use, my browser of choice, for now, is Firefox.