I voted as if I was a newcomer. To me, Rogue is obviously the hardest class because of the combo keyword. As someone said before, what you want generally is a 1 for 1 or 2 for 1 card. But Rogue does not really work that way and it may be disturbing.
To me, the easiest class is Mage. As I said, it's not about decks you can play because Paladins and Hunters decks are way easier than Mage decks. But when you start the game, you have way more powerful class cards as a Mage than as Hunter and Paladins. This is why Mages were so powerful in arena (pre-TGT).
Rogue is the most difficult to play by far. Due to the nature of the combo mechanic, you're always piecing together the cost/ability/synergy of more than one card. No other classes forces you to do this. And it isn't always clear what the best combo is either because this isn't a OTK combo but will just get you through the turn.
The reliance on the hero ability complicates this even further as it often turns out to be a part of many Rogue combos you need. All in all, it's simply a complicated class to play.
I think Paladin is easiest to play. I vote Paladin over Hunter because Paladin lacks removal (or at least lots of good, efficient removal) and deciding how to play removal requires a little more critical thinking.
I'm really surprised no one mentioned Combo druid yet. It is very a easy yet very powerful deck imho. Even tempo mage is harder due to its rng nature since you need to know when going for risky plays and whether it is worth it or not.
Everyone says rogue or shaman is hard but I think you are making misconception about hard and weak deck. I agree they are hard to play but playing freeze mage is probably harder than playing shaman, its sheer power is just much higher
Rogue is probably the most strategically difficult and Priest is probably the most difficult due to their class card pool. IMO.
Shaman is the least difficult/most unbalanced at the moment and if anyone disagrees with me on that you either main a shaman or are lying to yourself. lol
Rogue is for sure the most difficult class mostly due to their combo theme always being in the evergreen set and cards like prep being super strong but hard to use and time well.
Shaman is certainly not the easiest to play. It's really easy now due to having a stupidly good curve but overall as a class the random elements they have in their hero power, aoe, etc make it fairly difficult.
The easiest class to play overall is probably hunter because since beta hunter has basically done the same thing and that's be aggressive, push tempo and go face. It isn't their fault though since their hero power and cards basically make people go face a lot. Druid is also fairly straight forward until recently because 90% of the decks were just ramp, play bug things and finish with force roar combo.