WoW is a big tent and people have a myriad of in game goals, or no goals.
i try to set goals for myself that are challenging. I also like to mix it up.
in the m+ world, I like to get 2k score on a toon (I usually start with tank) and then go grab another toon.
looking at the crest system right now, I will probably do that with my guardian, and then farm enough +4s to get ~619 ilevel. i’m not a “get the portals” guy. after that, i will bomb around with my next toon. not sure yet if that will be another tank or healer or dps.