I would use
.com for international sites and redirect the
.es domain to
.com since the extension really is a country code, not a language code and
.com has developed into a general universal domain.
People from Mexico, Argentina, or Hispanics in the United States are probably not feeling adressed with a domain for Spain while they would be more with a
.com domain. Also, it will give your business or whatever a more international image.
Donít click this link!