The controllers and plugins has been created (and is being maintained) by a bunch of talented community members. Give them hugs and credit whenever you get a chance!
A few of the open source controllers can be installed on simple hardware such as Raspberry Pi or Cubieboard. A list of all known open source controllers is listed in this forum thread. They are probably all good candidates for new eager plugin developers.
If you need help creating a MySensors plugin for your favorite controller. Give us a shout in the forum.
In the menu you'll find a short description of each supported controller. Hopefully you'll find one that fits your needs.
Below a MySensors focussed controller comparison by active community members. The list show the MySensors related functionality and a list of Sensor (S_) and Variable (V_) types supported by the controller (if known). A description in the Serial protocol section. Additonal controller features can be found in the controller specific pages.
If you want to contribute i.e. add a controller or update information, please do so in the forum thread