I'm getting some cliparts from clipart.com.  Some of them are in both
.eps and .wmf format.  But I don't know which format to download.

With .wmf format, I can easily preview them with many viewers when I
need to pick one.  And they can be edited with Illustrator.  With .eps
files, I have to open the file in Illustrator to see what it actually
is.  That can be time consuming.  I'd say not practical at all.  But
what can be bad to have them in wmf instead of eps?