wich profession is the best one on GWF?

Honestly, the game is so balanced that any profession will get you through the game at the same pace. What's best really boils down to picking one that matches your personal play style. Little details for example like do you like playing a point and click tank that can stand up to any mistakes like a warrior, or a really delicate but high damage wielding assassin that can be really powerful but easy to get killed? Even a specific build can of each profession will play radically differently. My Minion Master Necromancers takes out enemies in a far different way then my guild mate's Curse oriented Necromancer.

there really is no best profession/class in he game as they have mentioned the game is really balanced and i appreciate that unlike other online games there is no uber class or build

Guild Wars revolves around balanced classes, and has managed to complete the goal; the classes are balanced. Every class serves to accomplish a variety of different purposes thanks to the ability to switch secondary profession. While Monks (for example) usually stick to healing and protecting they can also change their secondary and farm pretty good.

Some classes are however better for some purposes, an example of this is Paragons. Paragons are truly exceptional when it comes to relieving party members of pressure thanks to some skills making Paragons a class that pretty much everyone wants in their group, in PvE. However when they venture into the Underworld to farm for gold/greens (the best items) they are pretty much worthless alone.

I'll do my best to summarize what every class is about and what purpose you will mainly serve when playing that, but as always keep in mind that there are always exceptions due to the choice of secondary professions one can choose.

• Warrior: The Warrior serves the role of a traditional mêlée class: it can tank pretty good, it can provide the team with pretty decent support through shouts and it can deal very good damage. Warriors are usually looked for in PvP due to their ability to deal much damage, pretty much constantly.
• Ranger: The Ranger's role varies depending on if he/she is participating in PvE or PvP. In PvP the Ranger's main role is to interrupt and pressure through conditions. In PvE you will be dealing damage, this is mainly because interruption isn't as powerful as it is in PvP.
• Monk: The Monk exceeds all other professions when it comes to healing. You will always be questioned for because of your superior healing capabilities.
• Necromancer: The Necromancer's role varies a lot. If you decide to play a Necromancer you can play as pretty much every role there is in the game, however you will mainly be playing as a Minion Master.
• Mesmer: The Mesmer is fairly uncommon in PvE due to their lack of AoE damage and other support skills which tend to be good against larger mobs. Mesmer's are mostly popular in PvP thanks to their large number of hexes that can be used to effectively pressure both mêlée characters and casters.
• Elementalist: The Elementalist is a traditional nuker. You will mostly be equipped with damage dealing magic spells and use these to nuke your opponents to death. However the Elementalists also support their team with support and relieving of pressure through the use of Wards.
• Assassin: The Assassin is as you may have guessed from the name the usual "Glass Cannon". Assassins are mainly used thanks to their high damage.
• Ritualist: The Ritualist is another quasi-class. Thanks to the fact that they got both damage, healing and other support skills in their skill setup they are run differently. Sometimes you will be asked to support your team with spirits, sometimes with heals and sometimes with damage spells.
• Paragon: The Paragon supports the team with Chants and Shouts while still chucking spears at the opponents to pressure. Mainly looked after because of their almost extreme capabilities to remove any kind of pressure from the party.
• Dervish: The Dervish is yet another mêlée profession. Using mainly attack skills and a few enchantments to keep a rather high survivability while still being able to applying quite a lot pressure.

So when picking class keep this in mind, but also remember that there is always at least one exception to the rule.

Guild Wars gives you tons of customization freedom and no matter what profession combination you choose, you'll still be able to be successful one way or another. But do keep in mind that success isn't guaranteed. You have to work for it and find the best strategies to be successful. This is also a team oriented game, so you also have to think about what is required to make the team successful as a whole.

PvP and PvE will vary alot, and you'll have to change your skill sets to best suit the situation.