For me it was about FS95 before I got settled down to exploring more of what Flight Sim could do in a general aviation sort of way ... it was a big thrill learning navigation for the first time, taking off into heavy cloud and descending to find the Airport where it was supposed to be ... I do go back to FS2, but was only mucking around up until about FS95 ... that's when I started taking the hobby seriously.
The first military combat sim I loved was F-19 Stealth Fighter on the Amiga ... I can still remember dodging between the radars and keeping my stealth profile to a minimum ... the real F