Er, basically.. I'd prefer Opera over every other browser.
The reasons for it are quite several, actually. Opera is more customizable than Mozilla, even, with thousands of Widgets and a sidebar that keeps notes, widgets, transfers, history, and all links on one page organized brilliantly. It's one of the best browsers I've found so far, and I recommend it to anyone that I can find.
One of the greatest features of all is the 'Speed Dial', which is one of the most innovative features I've seen in any browser - even more, this feature is not available in IE, MF, Netscape, etc - only in Opera. What it does is when you open a new tab, or if you want, when you open the program, there are nine buttons under 'blank page' that are programmable with nine different websites. Once you click on one of the buttons, it takes you straight to it. It's faster than bookmarking, and you can still of course bookmark things as well. Most of you whilst reading this are probably thinking, "Pssh, I visit more sites than just nine daily," but it's actually kind of .. hard.. to fill up all nine spaces.
The wand feature is a bit lacking, but all it requires is clicking on the Wand Button or pressing CTRL+Enter, which autofills and logs into the page.. brilliant? Not as brilliant as Netscape's Log-In-As-Soon-As-Loaded feature, but still it's nice.
Opera is also the most space efficient browser of the four major (IE, MF, Netscape, Opera), topping out at around 4.5MB. It's one of the fastest browsers, as well as one of the most secure, incorporating various features that Mozilla FireFox only dreams of.
Plus, the two most major browsers, according to who all I talk to, are internet explorer and mozilla firefox, obviously, which means that over 99.9% of all malware/viruses are made for IE or MF specifically. Opera, being one of the least used browsers, has near no malware.
Here's what W3Schools said about opera's features:
"Opera has automatic Popup Blocking. This is fine for stopping annoying popup ads, but not so good for sites using popup windows in a good way.
Tabbed Browsing is a modern and time saving feature. It makes it possible to view many web pages in one browser window.
Transfers Panel is is Opera's download manager, with quick access to ongoing and recently finished downloads.
Opera's user interface is translated into multiple languages, and the language can be changed on the fly.
Opera has Customizable Toolbars, allowing the users to add and remove items as well as create new toolbars.
By choosing between different Skins, the users can change the look and feel of Opera.
Opera has direct access to Google's "related pages" feature, available from the "Navigation" menu.
Double clicking on a word on a page will pop up a menu that provides options related to the selected text, such as a Web, dictionary or encyclopedia search.
Opera provides Web authors with immediate access to Page Validation, thus encouraging good practices on the Web."
It also has RSS feeds, Google searching directly in the toolbar, hotkeys for everything,.. etc.
It's more customizable, safe, space-efficient, and fast than any browser I've tried. (And trust me, I've tried out every single browser. I've had my 'main browser' as Ie, Mozilla, Netscape, AOL, and Yahoo - I then found opera, spazzed, and used it for everything.)
Click here to view all of Opera's features/download it.