Long range, fast, (later on) stable damage.... Choose Gunslingers.
Short range, fastish (later on), huge mob damage.... Choose Brawlers.
It's definitely up to you and what your preferences are.
Most people usually give up their slingers, just cause they weren't patient enough.
You seem to want to lvl up fast, do strong damage and so on, so I'd recommend you a brawler.
El