Now having played every class and familiarized myself on how they work, I've come to the conclusion of what my favorite to least favorite is.
1. Mesmer - It has the best of every class. Two outstanding healing options (One that mimics what Necro CC use to be, and the other that is Warrior signet on steroids), stealth that rivals thief, great stun breakers that Warriors and Guardians would approve of, and top tier DPS if you play your cards right. Also brutal interrupts that rival Engineer, and ranged options that are almost on par with Ranger. You can play the AI and other players for fools. The only downside is how squishy you are, but as with all things Mesmer, you can make yourself seem invincible if you master the profession with all that deception. PvP offers a large variety of builds from instabursts, to longevity builds that can troll an entire team that is mediocre.
2. Guardian - Heals, Stun breaks, blocks, and condi cleanses for days. Group might, group heal, group fury, group aegis... The guardian can be near invulnerable... and carry a group through the toughest battles. Its my go to class for dungeons. Durability is unmatched and its group support is only bested by pro engineers. What it lacks in raw DPS, it makes up for in buffs and heals. It's by far the most deadly class in PvP when used correctly. Burn stacking is unrivaled and can take a whole team down when they aren't focusing you. Mobility is the biggest weakness... but in a PvE world completion environment, you can trait and set a weapons load out for permanent swiftness. Not to mention that using staff in that build is the most selfish loot tagging build in the entire game.
3. Ranger - Range, range, and more range... pew pew pew. LB is the weapon of choice for PvE. Press 2 to win, Press 4 to invoke rage. Rangers have the highest baseline ranged attacks in the game... melee weapons suffer huge flaws. Greatsword is a glorified swiftness tool and axe is... well a show piece. Sword does amazing DPS, but its auto-attack bugs out dodge ability, and its evade attacks are wonky and bugged. Despite that, Ranger has access to insane stability, and decent stealth. Condi cleanse its a weakness, but mobility and extra evades are the counter balance to this. Like Mesmer, Ranger class has high survivablity in fights that last longer than usual. The downstate abilities are by far the best of all classes in terms of the ability to rally. You can trait a heal skill to trigger, and your pet can revive you as well if you can survive the cool down. Bleed build is powerful in PvP along with power builds and the more hard to master stealth trapper.
4. Necromancer - The most neglected class in the game, but one of the most delightful in PvE. Its the most tanky class, and it needs to be because its best weapon is the dagger. Dagger is high DPS, and high life force generation. Deathshroud is a saving grace of solid DPS, and delaying the inevitable. Necromancer has unrivaled condi transfer and durability that almost rivals guardians. The downside is limited weapons types that are underwhelming and have their share of issues. Group support is limited making it a shunned class in more difficult group content. In PvP it can be outright deadly in the right situation.... the down state DPS is unmatched, and above all else, you can stall the hell out of teams from capping points.
5. Warrior - Unlimited stun breaks, huge group support, high DPS and HP. This class definitely requires the least amount of skill to operate. The class has access to the most weapons types but lacks any good condition damage. With high DPS and HP, comes limited healing. You think Necro has it bad when it comes to healing because of their "2nd life bar aka Deathshroud"? Warriors have it worse. It's kill or be killed. Despite the lack of healing, Warrior has perm swiftness abilities along with a ton of CC. In a selfish build you can be invulnerable to conditions and direct damage. Greatsword and Hammer skills are unmatched by any other class, and a pro can win outnumbered fights easily in PvP. It doesn't have the burst damage of Mesmer, or the burn DPS of guardians... but against any other class, Warrior is super deadly.
6. Engineer - Huge group support, decent DPS, amazing stuns. Engi is the most complex class in the game. Its base weapons are very bad making you rely on the tool kits for your main attacks. In PvE you have the highest DPS of any class in condi builds in extended fights... otherwise you are the middle of the road in everything. This class is the jack of all trades. You're not going to really beat anyone in PvP that has full HP... but you can delay the hell out of them. In PvE normal length fights your job is to keep everyone alive, and buff them. It's a true underdog class... but when traited right, you have unlimited swiftness.... making your delay ability in PvP valuable for decap in conquest.
7. Elementalist - Massive AoE DPS, and group heal make this class ideal for PvE and WvW. However its only for those that really enjoy non stop pounding on the keyboard. To get the most DPS out of this class, no matter what weapon you use, you have to constantly rotate your attacks between attunements. Extra dodges and healing can make this class present a problem for a lot of PvP teams... but since its DPS relies on AoE attacks and conditions, Ele can never win 1v1 against a decent Burn Guard, Mesmer, Ranger, or Thief. Their HP is too low, and while their sustain is decent, the onslaught of single target damage is too much for them... this class lacks any single target damage outside of D/F. And even then, dagger main hand is not good for classes that can block or dodge more than twice.
8. Thief - For pro players of this profession, you're nearly unbeatable... Thief has the highest single target DPS in the game... its the only class that doesn't have cool downs for its attacks... instead you have an initiative meter that regulates your attack ability... the more powerful the attack, the more initiative it consumes at the price of spamming it more than once instantly. Group stealth options make Thief desirable in dungeons for skipping mobs. It's unreal speed with shortbow along with a slew of traits, skills, and signets make it most wanted in PvP conquest. Decapping points is a specialty, and on the map Legacy of Foefire, the ability to solo kill the other team's Lord is invaluable. However, the class is super unforgiving and you will die faster than any class in the game with one wrong move.... even a good thief cannot 1v1 a good Guard, Mesmer, or Necro... these classes can either outlast our competitively stealth the class... and/or block their super deadly backstabs.
Revenant isn't finalized yet, but I'd put it under Warrior right now... the elite specs have the potential to shift these rankings.