Sony A37 vs Nikon D3200

hi...

i am searching for a DSLR camera for last one month. i narrowed my search to Nikon d3200.
now i found sony a37 also comes under my budget.
Also it is having some good feature.
the sensor size for A37 is little bigger than D3200..
In terms of processing power and image quality and performace which is good???
Also what about canon 550d and Nikon d5100???

Since canon 550d laucnhed 2years ago.. i almost droped that option.. but still i dont know about its processing power and image quality...

please suggest....

thanks
Vipin