All have their strengths and weakness. Safari is good for its speed, Opera is good for security and features that bundled, Firefox has the addons advantage. Finally IE sucks big time in all categories.
That pretty much sums it up. Except what exactly are IE strengths?
Security.. IIRC IE runs in a sandbox, so if you're going to be browsing sites with shitloads of viruses, spyware and other funny objects (read: porn sites), use IE.
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