Which micro-controller to use?

I am designing a voice activated system for my little sister who is a quadriplegic so she can view her iPad and talk to Siri by herself. I am searching for the best voice recognition micro-controller compatible with "Arduino uno" on the market in terms of quality, performance, and noise cancellation abilities. Any advice on this matter will be greatly appreciated and valued highly.

You can contact me via reply below, or by email: greg.fiordalisi2@Gmail.com

Thank you for your help!

The only Voice Recognition hardware I know of for Arduino is the $50 "EasyVR" shield:

She can get voice access to Siri if you install IOS 8, plug the iPad into a charger, and enable the "Hey Siri" feature.

You can start with EasyVR, it is certainly not the best, but it is a start.
There some examples of it on Youtube.

For good quality you need a computer with a good microphone and Dragon NaturallySpeaking speech recognition software. Even then, it might not work very well. The Dragon NaturallySpeaking software doesn't like my voice, it recognized between 50% and 90% of what I say.
You can make that "compatible" with Arduino by connecting an Arduino to the computer.

Is Siri working well for your sister ?
Perhaps you can connect the iPad to an Arduino.
You would have to build an app, or do something like this : Control Arduino Wirelessly With iPhone iPad iPod Using iArduino App - YouTube

What do you want to do with the Arduino board ?

If you just want a way to activate Siri remotely, you can also do it via Bluetooth, but the 'Hey Siri' feature mentioned above works well if you're plugged in to the charger.

Ian.