To me its all the same....a browser is a browser and now they all have pretty much the same features. I have IE7, FireFox, Maxthon, MyIE2(basically old maxthon), Opera, and Netscape(Mozilla based) on my comp. I used to have others but of course they were old and eventually I got rid of them.
They ALL basically have the same features now...its like eating a starburst candy. You may like one flavor more than the other but its still a starburst.
For security purposes a person should avoid IE7(unless you have a very secure network <---5 Firewalls), Firefox has security but not nearly as much as it used to do to the fact its popularity has Sky-rocketed since its release, Maxthon/MyIE2 has good security and is Skinnable which is a plus but it cant view transparent images(makes the background orange), Opera is actually pretty old but trustworthy and is best with downloading files(It even has a packaged torrent plugin making it much easier then using your own plugins), Netscape is now mozilla based so its basically just a different looking firefox

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As for other differences.....looks...and...thats about it. They now all tab and all have very similar features really...a person should just try them all and see which one he/she likes best.

There are way more than just these I have said and there are plenty that specialize in specific interest.
examples: LoliFox = Firefox for anime fans, uBrowser = FireFox in 3D cube based on OpenGL, UltraBroswer = A pretty IE with a very advanced and light weight GUI and so forth. 3B = Crazy webbrowser which makes your websites into a city/giant mall of sorts.
edit: oh and as for speed....its only a browser so they all move about the same. Maxthon can actually close tabs with a double click unlike firefox so technically a person can....move faster when closing things

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edit num2: for any who want to know specific differences check it out
http://en.wikipedia.org/wiki/Comparison_of_web_browsers