My observations from mainly running a druid in boss fights and getting to observe the death/aggro dynamics while trying to keep everyone alive, and also running a rogue for farming and lvling w/ my druid. I used to use a ranger but gave it up since I didn't like it much. Don't have much personal warrior experience (got one to lvl 35 and got bored of it).1. which is the best best dps
2. which is the best all around
3. which in your opinion is more fun
4. which is best for boss runs
1. Rogue: super dps on many quick skill with fast cool down rates. Mages have as high dps, but a) they weren't part of the original question, and b) their melee is usually terrible.
2. Rogue: useful in boss fights for dps/adds (although not the most useful... see 4), and definitely the best for lvling and farming IMO.
3. Depends on the person. Rogue if you like high hits and killing stuff fast. Ranger if you like tactical but slower fights. Rogue if you can lvl with a druid.
4. Druid.... err.. I mean... tie between ranger and warrior. They both have their niches. If I had to choose one I'd pick a warrior tank build with taunt maxed+. Ranger niche is bolas 100%, plus ranged damage to stay out of AOE and not bother the healer. Extremely useful on many bosses. Warrior niche is obvious: tank. I lean towards warrior because I'd rather heal in a boss fight with a warrior and no ranger than the other way around.
In the end, all of the classes are very useful in their own niche. Druids heal, rogues dps and adds, warrior tank, ranger bolas and range, and mage dps/lures. It changes if you want to solo a lot.
My $0.02 anways.