Then there is I-War (1+2), sometimes dubbed "Independence War" depending on region it was sold: Best Newtonian combat space sim I ever played.
Played Elite a lot around the mid 80's on the ZX Spectrum.
When I moved to PC and college got in the way, gaming became less of a priority, so I never heard about Elite II and FFE being released, and unfortunately never played them.
Afterwards my focus turned to flight sims, mostly the Microsoft series, but also played some space titles.
In the simulation genre the best for me were Independence War 1 (incl. the Defiance expansion) and 2.
Not only the newtonian space motion was very well modelled, as Navigare mentioned, it also featured free or flight assist modes, the 3 navigation modes we have in ED and a Power Distributor to balance power between systems, engines and weapons. Always wondered if those concepts were original to those titles, but I guess they existed already on previous games, like Elite II or FFE.
Although not being a sim, the Homeworld series was another space title that occupied a lot of my playing time.
Then in mid 2014 I accidentally saw online that ED was already on Beta phase after a successful kickstarter and became a beta backer.