With all you've listed, you won't have that much choice, it will be the 3 tank classes (sin, PT, jugg) and sorc. I don't remember if you wish to play dps only but i'll give you a quick resume:
Assassin: all specs good, despite deception (single target burst) being a bit behind because damage is basically near what we did in 2.9. Darkness may be difficult to handle for a beginner because lots of procs, but very good tank. Hatred is the faceroll mode.
I'd say assassin is an easy class to quickly obtain solid results ((like, play hatred) but not everyone play it at 100%, you need absolutely almost every ability in your hands. You have awesome mobility, awesome damage, awesome survivability but recently some are awesome s*cking at it.
Powertech: AP (single target burst) is currently the biggest burst of the game (rip carnage marauder), pyrotech (dots & cleave) is fun but needs to be fixed on everything, it's worse than in 2.9. The tank spec is the easiest to go atm and performs quite good: best damage potential, applies all his debuffs with one spell and basically poop on every melee comp (oil & aoe snare + harstun).
I'd say powertech is the class to go for beginners because everything is super easy, but 2 specs only are valuable. Note that you'll be first focused every time (unless you're facing incompetents) because any team who's not mentally retarded can't allow an AP PT to be free, and you don't have powerful defenses. With good focus, you die fast but unlike a merc/sniper/operative etc you will still have the chance to unload your full burst.
Juggernaut: One of the best classes for solo players because he's quite good at everything you can think of. The class is in a very good position atm, vengeance provides very high sustained with ok burst and a good dotspread, also can be one of the most annoying things for a healer. New rage has that good good burst which can surprise and destroy a target @60-70% hp. Unfortunately, due to the insane amount of roots everywhere, the tank spec can't shine like it did pre 3.0 (basically that's the only tank that can be brained & locked away with roots only).
Way more survivability and team utility than PT for example, but you'll need more buttons ('cause more defensives etc) so maybe harder, for the time you learn how to properly chain your CDs.
Sorcerer: IMO very good in all specs, you can carry like a boss with a sorc: bubbles, dispells, roots, stuns, off heals, pulls, cycloning stuff or utterly destroying people. Madness is the overall pressure dots spec, always good, you can prepare some extra burst by chaining some abilities (force leech, demolish, death field) and is super easy to handle. Lightning always had that very good burst, but lacked survivability. Now BW overdid it as always, the spec is ridiculous: you can trash people while backpeddling (yes, at the same time) how retarded is that ? So dps-wise, good buff in survivability mainly with instants and kitting, but you remain a sorc: squishy.
Healer spec is the easiest atm. While it used to be near decent but not very much at everything (burst, general output, survivability), it now performs very good at everything, without force management. Only merc is better, at burst heal.
You will instantly gain good results while playing sorc but there's a good gap between beginner and advanced-master player. Just one tip: don't think force storm is n1 prio in your rotation, you'll get destroyed. Once you're good sorc you can spam it if you have a fetish for numbers/trolling people but nothing more.
GLHF