I'm fond of the beautiful scenery + ship interior + EVA as they were handled and used by SC. The seamless transition between all those gameplays is a huge selling point for me. For instance, one of the mission that impress me a lot is when you have to seek corpses in EVA in a wreck floating in dark space, your ship stopped near the wreck to light it. I like also a lot doing some FPS so having a space game + fps at the same time is a must (EDO is a huge improvment of Elite for me).
I like a lot X4 but it has no multi.
I don't know Tachyon, I will look at it.
Tachyon is an oldish space sim but it had a good story, good combat, and good mechanics overall.
As for the rest, i can understand why you like SC (if you are willing to overlook a whole range of issues with the project), i just can't understand the claim to liking it more than any other space game ever.
And its not just you, i've seen this claim from many of the faithful.
It always makes me assume people haven't played... other games... ever.