rasberypi B+ or andurino for multi sensor project

I will carry on my project which I have start with 8051 cosis of 5 senser send result to pc and end up in very slow process. I just want to know between rasberypi B+ or andurino (Arduino Due)for multi sensor project which one should I pic also

Can you tell us more about your project.
What would the raspberry B+ or Arduino Due be doing ?

8051 is slow in doing what? Well I don't think 8051 will be slow in handling 5 sensors.you need to provide more information what sensors are you using and how they are connected to controller. For sure raspberry pi will be an overkill for such a small small requirement.