Which ARM micro controller should I choose?

Hi,

I'm taking up a major project for my final year in college through which I plan on learning about the ARM architecture.

I want to build my own custom development board instead of using a pre-designed one. I understand the time and effort this will take and my professors and mentors will help me through this process.

My requirements are:

1. I need the development board to run be able to run embedded linux. I don't need it to run embedded linux but I would prefer to program it in C/C++ instead of ASM. This is my only reason to run it on embedded linux.

2. Wi-Fi is a must.

3. I will also be using voice recognition for voice commands(this is optional and I may skip it if not practical).

4. I will need to connect a few sensors and actuators.

5. Low power and long lasting on battery.

6. An LCD or LED display.

As this is a project, I'm looking for cheaper options. I do not want to use something like an arduino or raspberry pi simply because I want to have this learning experience.

I'm a complete beginner in ARM architecture and honestly do not know where to start. I've programmed on an Atmel architecture in the past(on a pre-designed development board) as well as arduino. Also, please let me know if ARM isn't the way to go.

Thank you for taking the time to read this.

See ya!