I'd say 3 in about every way except the tracks and difficulty curve. The tracks are still good but kind of samey, and the difficulty of them is all over the place. Terminal is simply leagues behind Spilskinanke in terms of design, aesthetics, and difficulty. Meanwhile the hardest track in the game is the 6th one.
However the physics were never better, the music just as good, and ships didn't function simply as a "select your difficulty" kind of thing, each one having a playstyle beyond "controls worse and goes faster than the last"
They are both GOAT though.