Duo synergy with warrior
Thief – You get to “peel and cc” with hammer, while thief just backstabs and stomps everyone. You got decent survivability/disengage with both warrior and thief.
I think any class that do buff stacking and condi removal well is good. Since warrior is already tough and have high dps. Ur job is to take care of him, while he do his job.
Having a guardian with you is pretty nice if he’s focused on buffing you while you deal the damage. He can be offensively specced and still give decent buffs. Getting aegis, stability, protection and having conditions wiped fairly often while being healed is pretty nice. The only downside is him not being able to keep up with you cuz guardians are slow. Mesmer is also and option. I ran around for awhile with a Mesmer who had this weird build with a ton of stuns and dazes and stealths, and the enemy pretty much had to stand still and eat burst from both of us because of all the cc flying around. again, the only downside is them keeping up with you, but mesmers have stealth and teleports so they can get away better than guardian if things go bad. Engineer may be an option as well. Decent mobility, large amounts of cc, water fields for you to blast in and heal. Its a tricky class to play though. I’d still have to say guardian is best though as a partner, but this is just from personal preference.
Elementalist. It has lots of group utility . Probably say go dagger dagger as you can both rock everything in your path.
Warrior
Far Shiverpeaks
It depends on what build you play as the warrior. Assuming you play a typical Greatsword build for roaming, any class with with a means to apply immobilize or boonstrip are invaluable to a warrior.
Guardian or thief off the top of my head are fantastic with a warrior also. Guardian is just great defensive support and the burst and independence of a thief are useful. Thieves can also go 20 or 30 trickery for the boonrip and daze which is nice.