It all depends if you plan to play solo. Clerics have a tougher time soloing because of their low damage output. It is still doable but at a much slower pace.
Mages are very powerful, but requires a bit more of "skill" since you need to stay away from the mobs because of your low hp/defence (It is still one of the most powerful classes and very popular)
Like said above, archers are great for beginners and have lots of Area of effect skills (AoE) to help you on your journey.
Fighters and Tricksters are both melee classes. Fighters are more solid in terms of defence while Tricksters can deal more damage in a short period of time.
You should first decide if you'd like to play a melee or range dps. Then if you want to, write your class choice below and it'd be a pleasure for me to suggest you stat builds/skills for your class!
And welcome to Fiesta online