Wrong place as this is more of a question not a Guide.
Choosing your Fighter Subclass
Brawler - Not too great of a class at the beginning and begins to fall apart the further you go and become HIGHLY pinpoint gear dependent as most poisons will not be up to par with the level of monsters without such. This gear is rather hard to find but it will give you a + in some skills that is needed. PvP can also be difficult because of lack of comobs.
Grappler - Great for PvE Parties as a Hold Slave. In Terms of PvP it can be frustrating for either side. Based damage one making it one of the best PvE characters.
Nen Master - Balanced for PvE and PvP a Ranged/Spellcasting buff type. Not the easiest class but it becomes easier as you level and gain more skills and power. You'll be spamming Nen Shot a lot more than other skills though but this class is overall great.
Striker - Best PvP subclass for the class. Gear dependency is pretty high due to most if not all attacks are % based. Usually when a subclass is like this it means they are great for PvP. PvE can get... frustrating. You need to be point blank at all times and you're gonna get hit... a lot. Unlike Grappler which has invincibility frames this one doesn't have those but has a Super Armor buff.
Suggestion: Grappler PvE, Striker PvP, Nen Master Spell and Buffer, Brawler stay away.