今天最好的（便携式和可维护的）Shell Scripting语言是什么？

I know this question has kind-a started "religious" wars in past and there might not be one correct answer. But after working with ksh and csh for last 3-4 years and going through the pain of porting from one to another or applying a common piece of logic to multiple versions (read as legacy code), if I am writing a new script, I would go for ksh, but out of compulsion rather than choice. Is there a better option other than ksh/csh? Also something that is portable across Unixes (Solaris/HP/IBM/FreeBSD) and Linux (and if I am not asking too much or it if does make sense all Linux flavors)I know this question has kind-a started "religi