What controller should i use?
How about a Teensy? The guys that make Teensy have developed many of the well known Arduino libraries and have also helped develop the Arduino IDE in the past so they know their stuff.

I see the Teensy LC at about $11. the spec says its almost the same as Teensy 3.1 which has 20+ Analog In

https://www.pjrc.com/store/teensylc.html

https://www.pjrc.com/teensy/index.html

The 3.1 and 3.6 are more powerful and more expensive at around $29

note: Read the index for which boards are 5v tolerant if that's what you need.