Go to either Scania or Bera for normal pay to win play. Reboot if you don't want any help as you can't trade. Although you can buy cash shop items with mesos in reboot only.
Don't worry about the best gear because as soon as you get it, it will become obsolete anyway. Same goes with choosing the strongest char because by the time you're a super high level, that will change anyway.
Thieves gear still cost the most.
The built in game guide is a surprisingly good place to start. Make friends to help you.