Most needed dungeon profession?
Unfortunately warriors rule. Guardians and elementalists are welcome. Rogues, engineers and mesmers in limited numbers. Necros and rangers are not looked at favorably.
Well, thats the way it seems to play out to me.
In a little more depth:
Warriors are wanted for their high health and armour, and high reliable damage output, making many difficult tasks somewhat easier since they can absorb a lot of damage. They’re “easy mode”, and as long as you’re not terrible and you know the path you should be welcome in a PuG as a War.
Guardians are wanted for their team utility, with heals, protection, blocks, some might stacking, some swiftness, and decent dps. They’re pretty much a staple, you’ll see one or two in each group for most organised dungeon runs.
Elementalists are wanted for high dps, might/fury stacking, and their conjured weapons (which gives one to the Ele and drops one for an ally to use). Conjures like the Frost Bow and Fiery Greatsword are very useful in many specific dungeon situations. Eles are squishy, but at least one is seen in most organised dungeon groups.
Mesmers bring some utility (portal and stealth are very useful for some parts of some paths) but are squishy and tend to lack the AoE damage output required for dungeons. They’re pretty situational.
Engineers… are in a very weird place in PvE. Roll one if you want, but if you join a lfg party you may get asked why you’re running it.
Thieves can do high single-target damage, and the long-duration stealth from Shadow Refuge is very useful for running through large, unimportant and enemy-filled sections of dungeon paths – or for ressing downed allies safely. They’re really very squishy against the powerful AoE attacks of many bosses.
Rangers lack many useful abilities for PvE, with low damage output from weapons, and reliance on conditions and pets. Since pets don’t dodge attacks and their activated skills are… unreliable… the Ranger is seen as a bad choice for dungeons. Many other things, too – they were voted for some proper developer-player discussion well above all other classes recently, and a revamp is hopefully on the way at some point in the future.
Necromancers can bring some group utility, but lack AoE direct damage – and condition damage suffers from a number of problems in PvE, especially against the high-health bosses found in dungeons.
After rereading the thread before posting, I see the OP says they’ve not played for about half a year – sorry if you’re already experienced and I’ve gone into a lot of depth that you were already aware of.
As longshot says, Warrior is a safe bet, and Guards and Eles are also strong in the meta. It’s possible to run any class if you play well, but these three classes are reliably useful for the majority of dungeon paths, with others only occasionally being in demand.