The consensus amongst pretty much all the good players I can think of, from people I know personally (not saying much since it's the southern hemisphere, but I know most of the top players around here) to the top players in the world, is that Strikers or either Hunter Class are the best. Sunsingers having terrible movement options and a very lackluster super being a particular problem for them.

I'm not sure where you're going with that whole response though. Other people being able to damage you is a factor under the skill requirement and risk of the super. GG has the longest ranged kill and highest kill streak potential (arguable with AB) in return for no healing or armour options. That just means that you have to know what you're doing.

Part of the reason I said particular players' skill, especially bad players, shouldn't be considered though, is because it's true of everything. Fist of Havoc is rubbish in the hands of a crap Titan, and incredible in the hands of AEGabriel. Golden Gun is pretty crap in my hands (I mostly blade dance when I'm rolling hunter, and I'm hardly OP at that either), but I know several players who will almost invariably get 4+ kills with it, usually dependent on enemy clumping. Same goes for the classes. Several of the top players in the world play almost exclusively as Titans or Warlocks, with no real experience as the other classes. In their hands, the differences between classes don't matter than much.

I do actually agree with much of what you're saying in this comment, I find Sunsingers a real bitch to deal with sometimes (read: when I'm not more than 20 feet away from them and can just one shot them), but I don't think it's a class that takes any less skill to be awesome with than hunters or, arguably, titans (though Defenders are a bit iffy).