Kaleban,
1) That’s a loaded question. The specs of these classes just play so different. For the purposes of cliche answers, I’m going to assume that you’re playing some kind of stealth dependent dps spiking Thief and some kind of elixer grenade AoE dps Engineer. (Those are some of the most currently popular specs, though they are just a sample of these classes.)
If you asked people at this very moment, it would be Thief. Engineers have a poor reputation, which really isn’t very fair to them. The concept of the “boom head shot” stealth Thief is still alive and well. Your grenade Engineer would put out very respectable damage, but the obsession with Thief and stealth is still at the front of people’s minds.
Having said that, stealth just got hit with the nerf bat. Based on many people still whinning, I’m guessing that it will be nerfed again within the next 3-6 months. At the same time, ArenaNet has basically said that the cliche burst Thief is just too bursty. In theory, this will likely mean that Thief will lose burst potential for an increased dps output over longer periods of time.
Your question is sadly ironic because you’ve picked two classes which I consider to be in a state of flux. There are far too many Engineers who feel like they are playing an unfinished class and feel that ArenaNet doesn’t know what they’re exactly doing with the future of the Engineer. At the same time, it seems that the current incarnation of the Thief is likely going to see some serious overhaul within the next 3-6 months. No matter which class you choose right now, it will probably look noticeably different in the coming future.
2) Right now, I’d say the assassinating stealth Thief. Yet as I just covered in Question #1, this answer may seriously change in the coming months.
3) Most of your average Thief builds will run a dagger in your off-hand slot for the stealth spamming. Beyond that, you’re got the face tanking sword/pistol build and the sub-par pistol/pistol build. While my own Thief uses s/p and runs the AoE buffing Venomous Aura spec for PvE, I’m the exception to the rule and my build is considered to be a bit moronic by a stealth Thief since my build “doesn’t play like a Thief”. There are a lot of different ways to build your stealth spammer, but they all come down to spamming stealth (which seems to be a primary nerf target by ArenaNet).
Engineer specs have a lot more variety. Between their various skill kit weapons, you can easily devote yourself to a single kit weapon or you can run a couple of them at the same time. I run x2 Engineers and both of them play noticably different. Having said this, their turret spec line is still considered to be sub-par by a lot of Engineers since only the turrets’ dps output was increased and nothing has been done for the turret being able to survive a battle. Right now, Engineer has a lot of options. Yet you can also debate over just how functional or valuable these various specs are.
4) Fun is a subjective thing. I’ve currently got x2 Warriors, x2 Engineers, and my Thief primary character. When I do make a 6th character, I do intend to make a 2nd Thief. With that in mind, I’d say that there is easily enough variety in both Thief and Engineer to make multiple characters for each class. That’s pretty fun by itself. But having said that, it would have to be my Thief because my total spec lets me do everything that I love in a MMO class. I can fight in melee with relative safety, I’m hard to put down, I’m a debuffing machine (which is a pathological need in me), I’m a player buffing machine (thanks to Venomous Aura), my dps output is respectable, I can easily solo, and I can provide abilities that are very rarely seen in the game (since far too few people run Venomous Aura and Basilisk Venom).
To be completely honest, you need to figure out what kind of playstyle would be the most satisfying to you. Do you want to AoE heal, AoE buff, debuff, single target dps, AoE dps, fight in ranged combat, or fight in melee combat? Once you’ve picked out the qualities that you consider to be the most important, look through the skills and traits of each class to see if you can find a spec that meets your needs. Then try to take a glance through the forums to verify if that spec is relatively viable.
EDIT
WTH! I just took this long to respond to a necro post? Grr…
We are Test Group F. (Don’t ask about what happened to the previous Test Groups.)
