Why not offering 3 modes?
"Nerd mode": Give some hint in the quest text towards the location of the quest objective or the mob to slay and which direction or area it "could be found", but no arrow and no guide towards completion.
"Casual mode": Give text infos about the quest objective, highlight an area in the map and add some markers on relevant mobs or objects (e.g. a "!" icon next to the mob's nameplate, a "glow" border around objects / herbs / etc. to collect for the quest, and similar).
"Navi mode": Give them basically a navigation system towards the specific mob(s), make it very easy to find (dotted lines for how to run there the fastest way), and make it really easy and fast to complete quests.
This way, the player can choose what suits him or her most. Sometimes it is also depending on one's mood which mode to use. Some love to "play detective", some others just want to get to max. Level and endgame the fastest way and only see a necessary evil in quests.
Give the choice to the players - let them choose and change their questing mode within seconds.
Kind regards
Wolle