You probably don't want Expos because this seems more Washington themed, but if you were to include that part of the franchise history, then Gary Carter, Andre Dawson, and Tim Raines would be the best choices (even over Pedro Martinez and Larry Walker, who were stars in Montreal in the early 90s but blossomed elsewhere).
You are missing one of the single greatest Expos on that list. The guy who got me into baseball, Mr. Vladimir Guerrero.