Dingux
Pros:
* a modern and actively developed system
* avaliability of programming languages
* avaliability of applications/libraries
Cons:
* problems with SD card filesystem stability
* lack of hardware support (tv-out, radio)
Native OS:
Pros:
* comes preinstalled
* full hardware support
Cons:
* emulators violate GPL
* lack of support and vital updates
* lack of applications/libraries
* ports require a mayor rewrite
For writing new games with an eye towards portability to PSP, Wiz and possibly NDS what would be a best approach?
Definitely Dingux. Especially for Wiz.