This is a tough one to answer.
The top one right now
I'd have to go with is FFG's Star War Edge of the Empire and Age of
Rebellion. That is by book count on my shelf at this time. In that
regard, the 2nd would be Doctor Who.
But as for style, presentation, setting, rules, and artwork- Rocket Age.
product line is wonderful. This is one of the most solid apologetic
versions of the Flash Gordon/Buck Rogers genre. Great stuff.