The Eternal Debate: "Like" vs. "When" Inheritance

First: Happy New Year, Specmaniacs!

Much like the rivarly between the New York Yankees and the Boston Red Sox (or if you prefer, ManU vs. Chelsea, or the Tokyo Giants vs. Hanshin Tigers, or [insert a cricket example here]), Specmaniacs have been divided into two competing camps, with one group favoring "when inheritance", and the other "like inheritance".

Before R&D and others from Team Specman elaborate on this topic in a subsequent post, which construct do you favor, and why?