Every MMO plays a little bit differently. We all know that, just like we all know that goes beyond something as simple as “in this game there are no guns.” Sometimes in a given game, melee damage is the best option you have; other times ranged damage is insanely strong. Sometimes ranged weapons outpace magical spells and sometimes an arrow is naught but a piddling caress compared to the grand might of a fireball. You get the idea.
That having been said, most people do not go into games they have not played before as blank slates content to simply pick whatever options are most efficient with no concern given to anything else. So how do you pick your playstyle in a new MMO? Is it because you pick a couple options that you always gravitate toward (spellcasting or dual-wielding or support options) and then build more on top of that? Is it dictated by the character you pick? Do you just try to pick something different from what you played last?