Not sure what are you basing your list off... lore? most extreme examples? personal fancy? Feels like the latter.
If one would judge from a lore stand point and not focus on extremes but rather take an overall look on representation:
Warlocks are indeed are a league of their own. Pretty much all mentions of them are either them being corrupted by demons, being demons or trying to get close to demons. The other two candidates for high rankings would be deathknights and shadow priests, and while shadow priests don't generally have redeeming factors, only the scorge deathknights were focused purely on evil, while the current ones and, more imporantly, the original, orc created deathnights, are more focused on their goals and well being rather then world destruction.
Now the big "middle pack" of classes, who don't really have any affinity either side. Many would claim rogues are bad, but in reality, alliance rogues are regarded as nothing worse than spies, which is not as glamours as movies make it out, but is still just a job. Horde rogues are a bit of a different story, mainly assassins and are treated only slightly better than warlocks, but in reality they cause less bloodshed than your ordinary grunt, it's just their ways are not celebrated. Mages, even though walking the thin line of temptation, are generally tend to be selfish and self absorbent, but not evil. If anything, I would rank hunters worse than the previous two, simply cause majority of them, or I should probably say rangers, are generally rather hostile to anyone who's not an elf. They won't go out of their way to invade places and torture the innocents, but just shooting you would be a common derision, instead of a greeting.
Warriors are the immovable middle. Gray ground. Just too many examples of both good and evil ones, so so many more simply are neither.
And now the would be "good guys". A driud would be the first. Connected to the nature, they will do a lot to protect it. You would not wanna be in their way. Priests (no shadow) will follow, cause they are sworn to Light to protect the weak and innocent, but their oath is one to a man, so sometimes it's broken. Second to best will be shamen, reliant on the element to acquire their powers, they simply cannot do bad for long, as you can see in the books about orc past on Draenor. They often have to justify their actions tot eh element to revive the power and so far there's only one shaman who can pull incredible energies to his bidding on a regular basis, so it won't be a trend any time soon.
And the purest would be paladin, no surprise. Yes, we have examples (mainly one actually) of them going bad, but the funny thing, they would loose their power long
before completely committing to an evil lifestyle. Paladin would loose all the powers of the light if he ever steps on the dark path, leaving us with a warrior at best.
I did not mentioned the monk deliberately, mainly cause they really do't have that much of a presence in lore right now. They seem kind enough to teach most races in their ways and are tolerant of anyone, but they only have their teachings to guide them and no oath or greater power to help them, so there's an unlimited potential for some good old ultraviolence.