Alias or Environment Variable -- is one better?

In a batch file, I can do this:

alias wrar = "C:\Program Files\WinRAR\Rar.exe" a -r -idcdp -m5 -rr10
Then when I want to create a RAR archive I can just do:
wrar archivename

I can also do this:
set wrar = "C:\Program Files\WinRAR\Rar.exe" a -r -idcdp -m5 -rr10
And then create a RAR archive with:
%wrar archivename

I've done it both ways and they both work. Is one better or preferable to the other?