I'm surprised that the blackguard is rated so low. As others have said before, late game its by far the best class, and I would argue that starting with a blackguard is not that hard, since you can easily kill animals with it and feast on hefty meat stews that will keep you going for a long time. The drop rate penalty applies only to loot vessels, which rarely ever have anything useful in them anyway. My opinion is that the malefactor is the worst class because none of its bonuses matter mid to end game. At least the clockmaker has a useful rebate on TL repairs (though, again, I'd rather kill more drifters with the Blackguard and loot a ton of temporal gears, than struggle to kill monsters and save on temporal gears) and the tailor can make unique stuff (for now).
The best class is either the blackguard, or the hunter (in multiplayer to avoid ore penalty). The blackguard is though, can take a beating and deals good damage up close, but nothing can even come close to the damage output of the hunter when chain throwing bronze spears (or even obsidian spears!). Everything else doesn't matter much, especially if you are a builder. The only thing that really matters is your character durability and the speed at which you can dispatch monsters when you get into battle. The tailor is special in that it can make unique items for now, so its in a different category, where you want at least one on your multiplayer server, and earns a silver medal for this reason.