That's a good question, OP, but ...... it all depends:
There is no ultimate goal in Elite, but there are in-game goals to complete so, in my case:
To achieve a goal of say, unlocking an Engineer, I use the ship as a tool to suit the purpose .... Cobra or Courier for combat (even the Keelback when I want company), Clipper or AspX for missions (passenger or cargo or both);
But ships can be a goal .... had to grind to get the Clipper, so had to use combat ships to achieve it.
Even a Suicidewinder can be a tool to get you home from somewhere very far away very fast ! [noob]