PvP and PvE classes.

Hey. I just got my Beta Key, but I don't want to make a mistake making a char without thinking. I love PvP, I don't really care about PvE so I want a char, which will be able to pwn at higher lvls. Are there any classes like this? I know that "you can be a ranger with sword", but I think, that in every game there are chars, which are more overpowered than the other. Thanks for your help.

This may sound like a parroting of common information, but if you actually want to be competitive you should stop treating PoE like other games on the market. There are no best or worst classes, just good and bad builds.

Since a class is nothing but a starting point the impact of your class choice means less and less the higher you level and further you progress into the tree. If your aim is low level PVP your class will have a very large impact, but still there is no clear winner. PVP is not a solved formula right now and I suspect the entire game will be prone to meta shifts with new items, gems, and preferred strategies.

This is a good thing. Actually learn the game if you want to do well.

All classes can fill all roles. You can be a Shadow or Ranger-based tank. You can be a Marauder wand-slinger. The real question you should be asking is:

What skills are best for PVP?
What skills are best for PVE?

When you know what active skills are best, then you can plan builds around them.

For instance, Ground Slam is a pretty good skill. Lots of people use it. But it can be built around in many diverse ways.

For one, I've made a CI 2h Witch which utilizies ondar's clasp and more meleee damage on full life and +52% aoe from passive skills. The effect is a very powerful, sustainable PVE build. Probably wouldn't do so well in PVP, as Ground Slam, even with faster attacks, is a very slow skill.

Shadow

You are right that there will be some that are more powerful than others but it has very very little to do with what character you choose. It is more dependent on your build, gear, and skill gems.