maple and chipkit require their own environment and libraries so they are not suitable for this project.
Have you looked at the chipkit environment? MPIDE is pretty close to Arduino.
Likewise the TI Tiva Launchpad, which uses Energia, which is also quite close to Arduino.
Your best bet is probably the PJRC Teensy 3.x, which has gone to more effort to keep close to the Arduino look&feel (and color scheme) , as well as putting a lot of effort into Library compatibility.
In the end, it will depend on which libraries you need to work. A lot of the 3rd party Arduino libraries are very AVR-specific, and won't run on ANY 32bit processor (including Due.)
Due is currently the only ARM microcontroller board (ie not Yun) supported officially by THE official Arduino IDE.