Raid geared rogues have always been in the top, especially when they have the back of a mob. They also have a much higher survivability rate then berserkers in the raid scene for the most part. Adding in poisons helped rogues even more. Non-raid geared, meh...I would go with Wizard or Monk though.
This.
When you see the posts from people saying rogues are tops, read what they say. In almost all cases, you'll see a reference to raid gear (which disqualifies the assertion due to the conditions in the first post).
In group gear, I'd go with a caster simply because they have it easier. All they need really is AA and you don't need 35 other people to get those for you.