Ubuntu.

For the first two weeks or so of using Ubuntu, I predominantly treated it as a kind of plaything -- a toy -- that I had no real serious intention of using in place of Windows. Oh how things have changed.

At first, I didn't really know what to do with Ubuntu -- typically the first thing I do when I install a new Windows is download Firefox, delete IE's shortcut, and go on a day-long googleathon to find and install all the programs I'm used to using.

Ubuntu was very different, since unlike Windows (or any other OS), it came pre-loaded with literally everything I needed from the get-go.
Firefox, a source code editor, GIMP, Pidgin, a movie player, even a very nice torrent download client. Furthermore, searching for programs didnt even require me to open the browser, since Add/Remove programs not only removed the programs(as in Windows), but also had a massive library of applications that I could simply check, and it would automatically download and install them for me without any extra work.

Probably the biggest thing that kept me using Windows though, was the games. Crysis, Call of Duty 4, Bioshock, Fallout 3, World of Goo -- all games which, at the time, I'd been pretty addicted to.

So my usage of linux was reduced to that of a few, hour-or-so long bursts every couple days or so.

I dont know what exactly caused it, but after about two weeks, I suddenly stopped looking at Ubuntu as a plaything, and actually started using it.
This is when Ubuntu, in my mind, not only beats Windows, but absolutely obliterates it.

Now since I can't be fucked compiling what I love about Ubuntu into coherent, flowing paragraphs, I'll just throw down a classic Top 10 List.

Here we go~

Things I love about Ubuntu

• All programs look consistent. While on Windows you've got things like Limewire/Frostwire, Windows Media Player, Opera, Winamp, and more programs that just dont look like they were meant to be on Windows, in Ubuntu everything looks nice and consistent.
• Video quality is, for some reason, better. I have no idea why either, though I'm definately not complaining.
• Gnome applets are so damn useful, I dunno if I could go without them.
• WINE actually runs Windows emulation software better than Windows itself does. xD
• I actually use the Applications menu(Ubuntu's equivalent of a Start menu), and as such have no program Icons on my desktop.
• NO REGISTRY.
• Ubuntu hasn't frozen on me, restarted my PC, or anything similar, ever. Unlike Windows XP.
• Wobbly Windows. I love them.
• No need to run defragmentation software or Virus scanners.
• Installation of programs is easy as fuck. Further than that, the OS itself was jarringly easy to install -- it instantly knew what drivers my GPU needed and everything!

To be honest, I actually havent booted into Windows in about a month, and I doubt I'll have any need to in the forseeable future either.