🚀 go-pugleaf

It is unreasonable to claim that PolyShell is
"better" than the MKS Toolkit (which includes
the MKS Korn Shell).

MKS has more utilities and has gone to a lot of
trouble to ensure that its utilities conform to
the System V definitions or the draft POSIX.2
Shell and Utilities interface as appropriate.  
(Note that the SVID covers A Lot that isn't mentioned
at all in POSIX.2 or POSIX.2a)

PolyShell hasn't really made much effort to 
follow the POSIX.2 effort.

Folks who prefer Berkeley-flavoured things like the
C Shell and who aren't very POSIX-oriented might well
prefer PolyShell.

Folks who are POSIX or System V oriented will be
much happier with the MKS Toolkit.

Both are fine products but a direct comparison along the
lines of "is rumoured to be better than" is uncalled for
since they really are targeting different customers 
(BSD people and SVID/POSIX people) and have different 
goals, capabilities, and limitations.  

The other consideration in comparing them is the matter of support
and MKS has a quite solid reputation for supporting its customers
while Polytron is dropping its support.  

On the other hand, a colleague here has been quite happy with the
shell described in "On Command" and with its accompanying utilities
from "/util" that M&T Publishing sells.  It doesn't do as much as
either PolyShell or the MKS Toolkit, but if it meets your needs then
it is a reasonable way to save money.

I believe that there is also a product called the "Hamilton C Shell"
from yet another vendor.  I don't have much information since I'm
a Korn Shell user and csh just doesn't interest me.