I did mage/warrior. Did not mesh well.
mage is great class if they ever freakin' fix it. gets really annoying to solo around level 25.
Still...you can solo pretty all of the boss mobs (not crowns). Elites are ok to solo as well, just as long as they are a few levels below you. Mage might be better to play at 25 once they fix the Passive skills, which at the moment do not work.
After I asked what class was best to solo with, I got a lot of Rogue/Knight suggestions.
So, currently I am leveling a Rogue/Knight, and I have to say I am loving it. I'm at 15/14 at the moment, but so far so good. I do great damage, kill crazy fast, can take a beating, and that's that... Boss mobs give me a few issues. (not crowns) I cannot solo them as easily as I could on my mage, but I haven't had any trouble finding groups to do the job.
I don't know how I stand against Elites yet.
I never really leveled my warrior side of the Mage/Warrior combo...
Priest - they absolutely suck at PvP. The devs. really broke them when it comes to PvP. Now Pve is a different story. I've partied two Priest that tanked better than the warriors, or knights in the party. Hell, I was in a party in Abbey in which the Priest was the tank, and we cleared Abbey. Preist kill slower than mage from what I have observed, but have a much higher survivability. Unlike mage, priest can use a shield, which really buffs their defense.
I've never played Priest, so I'm pretty much talking out of my ass, but that is what I have personally observed from partying priest, and dueling them.
Scout sucks, everyone I have seen playing scout hates it. Scout is very underpowered.