LogFAQs > #941850953

So really the only class that you really need to unlock via the newbie reroll would be Gretel - Minstrel as Gretel is currently the only Minstrel in game. Everything else has either multiple characters with access to it or is freely available (I believe Alice is the only Mage available right now)

With that being said other characters will unlock Minstrel over time and at a quick glance, it seems that Red Riding Hoods Minstrel comes via event which will be free to obtain and not that far down the line (about 2 months depending on how the early Nier collab effects the schedule). Every other Minstrel looks to be Gacha only or way down the line.

------------------

Ideally you want to unlock as many classes as possible regardless because as you upgrade classes (and you'll upgrade everything you get as it's not hard) they give two types of bonuses

Class - Only applies when you are using that character and class (I.e. Cinderalla Breaker Class bonus does not apply when using Alice Breaker)

Common - Applies to all classes at all times (These are typically just stat boosts)