DrDiettrich:
Why don't you use one of the Arduino supported controllers, and design your own PCB around it?
I agree, design your own PCB using a atmega2560 or similar
I would not use a PIC32 - the harmony software is complex and has a very steep learning curve - on several projects end users requested a PIC32 (e.g. a modern uptodate 32bit processor!) - in the end the PIC32s were replaced with PIC24s
we have just developed a prototype system using an Arduino MKRFOX1200
the final PCB will use a PIC24 - in the main because we have designed numerous PCBs with PIC24s and see no major problem porting the code