Electronic – Embedded C programming material

If you really want to learn about microcontrollers, then ditching the arduino and all its layers that hide the details from you is necessary. A PIC 16 is certainly one bare microcontroller.

You definitaly want to use MPLAB, at least for debugging. Using anything else makes no sense, as MPLAB is free and officially supported by the manufacturer. Microchip now also has a full line of compilers that are free, with the only difference from the full versions in that some optimizations are turned off. That should be of no consequence for someone learning and experimenting, and you get to use the same compilers most other people are using and that therefore have the most eyes catching bugs.

However, if your aim is to really learn something, you should do a few projects in assembler. This will force you to learn the lower levels and open your eyes to what really goes on at the hardware and instruction level. That insight is very useful even when writing higher level code, and you won't be reluctant to implement a key module here and there in assembler as it may be appropriate.

I suggest you get a Discovery Kit for STM32 F4 Series with STM32F407VG MCU like this one. This is an absolute steal for $14.88. The 32-bit ARM Cortex-M4 processor has 1 MB of flash and a 192K of RAM. It also includes two PWM's for motor control.

You can expand the I/O using this STM32F4 Discovery Shield. It allows the addition of up to four Click boards, such as Bluetooth, Wi-Fi, and dozens of others. Unfortunately, no H-bridges -- but there is a prototype Click board where you could wire your own.