What would the subway rankings be (based on Seoul)?

I mean as a mode of transportation, not in terms of facilities.
Personally, I would rank them as:
Line 2 > Line 9 > Line 3 > Line 5 > Shinbundang >>>> Line 1 > Line 7 > Line 8 > Line 4 >>>> Line 6
This is my take, what do you think?
First of all, it's certain that Line 2 is the undisputed #1.
Line 9 covers Yeouido + Gangnam core (Express Bus Terminal, Nonhyeon, etc.).
Line 3 covers the city center core (Gwanghwamun, Euljiro) + parts of Gangnam (though not the main business hubs).
Line 5 covers Yeouido + the city center core (Gwanghwamun).
The Shinbundang Line covers the Gangnam core + Pangyo.
That's how I viewed it.
Line 1 has old cars, but it hits the city center core (Jongno, Gwanghwamun, Jonggak).
Line 7 has good accessibility to Gangnam, but doesn't go to the core Gangnam districts (only around Nonhyeon).
Line 8 doesn't pass through major business districts.
The same goes for Line 4.
Line 6 is out of the running.
That's my general thought.
Since in Seoul, accessibility to the three major business districts + other business hubs is everything...