The main reason I will not go for a console is the fact that Analog Sticks and buttons aren't as precise and as quick as a classic keyboard and mouse. I can aim better as well as switch weapons much quicker, not to mention on Valve games, I can bin things such as noclip, explode
and kill to my keys on my keyboard. That, plus gearing towards the Xbox 360, the PC online is typically free (unless you come across WoW). On the side of modding, consoles have very limited ways in terms of modding. This is what makes the PC superior when it comes down to gaming, as not only can you build your own mods on a PC, you can run them, distribute them, etc without having to hack the console, software, etc.
PCs themselves typically have faster hardware too, while game consoles typically have games with better optimization. Take Crysis for example, or Grand Theft Auto IV. When you have your settings maxed as well as antialiasing (one thing consoles RARELY have enabled! Jaggies are terrible) maxed, games look beautiful and if you have the power, they run great as well. On the side of optimization, it is much harder to optimize a PC game though considering there's millions of different combinations that could be going on, such as the hardware, software, etc, where as a console typically is mass produced with the same hardware, and the only thing to really worry about are certified 3rd party accessories and software versions.
The only downfall on PC gaming is typically unknowledgeable users, crashes, and of course, the all hated DRM. Many times in my case when I meet a gamer who plays on their PC, they've always complained about lag, low framerates, crashes, etc and I've always have had to help them out to get their issues fixed out. Typically, it's the video card or RAM that's the issue with PCs. Crashes, another downfall on PC gaming. Sure, games are quite stable even on Beta Operating Systems, but due to drivers, 3rd party apps and tons of hardware configurations and settings, it's hard to not make a game crash on a PC for someone. Yes, console games do crash though. It happens when the console freezes and you have to quit the game or reset the console.
PCs though are useful for gaming too. You can record video, mix them up and everything without needing a PC or a video capture device. Not to mention, you can download games, have multiple hard drives with RAID arrays, upgrade the hardware, build your own system, customize it, etc. Also, for those times when people complain about lag, the PC has tools that you can use to find the source of the lag, including Command Prompt, and the internet browser.
With some thought I'd be able to get things down more, but this should be good enough. For me though, I wish that consoles would at least have antialiasing. Nothing looks worse in a game besides garbage textures that jaggies.
