Best build? Hmm, lets see. Probably either a Warrior, a Rogue, a Wizard, a Warlock, a Cleric or maybe a Bard.
There is no such thing as ''the best build in EVERYTHING''. Every build has its own things where it shines in. If you want damage, definately Wizard or Rogue. You want to be a tanker? Then you should go Warrior. Wanne be loved by everyone and be a healer, Cleric is the one for you! =) Like to dance? Shake your a$$, with your bard! Hmm, we have one left. That's the Warlock, the Warlock is like an hybrid char imo. It doesn't shine at 1 thing, but it's good at almost everything ;p
Parties are always searching for warriors, wizards and clerics. So if you like to party that's probably the best way to go.
A wizard can solo pretty well too, as long as the mobs don't come near.
Rogue can solo on it's own pretty good, but if it wants to do high damage it get's a more fragile build.
Warlocks are nice to have in a party, 'cause they can mobs weaker and stuff and they can solo pretty well too, 'cause they have a skill that leeches life, and they can stun.
As a Cleric you have 2 choices: Skip quests and go grind grind grind with your party. Or find a good friend/party to help you with quests, 'cause Clerics aren't good at attacking.
Bards can do very good dances, they make the party stronger and can fill up mana.
I'm sorry it might be a little bit of a mess, but it's hard to type so much in English, when it isn't your ''main language''. I hope you understand what I want to say tough.