Have always been a loyal Nintendo fan but started buying both Nintendo and Sony systems when the PS1 came out.  Bought 2 xbox 360s and both crapped out after a year.  Never will buy MS system again. 

From Sega to Sony in the 5th gen.

Never, Atari 2600( My first console, I was in my teens during the Atari, Intellivision console war.) ) ,NES,PS1,(PS2 and N64 at the same time).Dreamcast, GBASP, XBOX360, and PC. In the old days if there was something different on another system, (usually Sega). I would just rent it.

I have no allegiance
I did go from PS2 to Xbox then Xbox 360 to PS3 but I still own all of them. Only reason I bought an original Xbox was for Halo

I still like Sony, but I did switch my primary console from PS3 to 360 this gen. I'll most likely get PS4 though and be a Sony guy again.

Bought a wii then switched to a PS3 and never looked back.

I switched twice. First from the Xbox 360 in 2005, I loved it. Then I switched to a fat PS3 in 2008, I loved it at first when it was new, but then I realized the games weren't that great and the third party games looked like crap compared to Xbox 360. I switched back to Xbox in 2010 when the redesign came out. Games like Alan Wake, Gears 3 and the Kinect won me over.

Stayed on with PS3. Will be picking up a PS4 at launch. Not interested in the Wii U although I'm hoping that Microsoft will entice me more this time round.

Started with the 360 then moved to PS3 when the 360 stopped getting exclusive games outside of Halo, Gears and Kinect stuff. I'm not interested in Halo and Kinect. Gears interests me a bit, but after seen the trailer I don't really like the main character of the new game. The only other reasons I could think of to keep the 360 came to the PC (Fable, Alan Awake) so there was no reason to stay with it. I did love party chat though.

MS back to Sony. I have both but since 2009 I've spent more time on the PS3 since Sony has pretty much been dominating for four years straight.