No class is designed or able to take on heroic mobs solo and succeed consistently. some classes can take a green triple up now and then but remember that they are GROUP mobs and so, are designed to be beaten by a group of players! That's why they drop better loot and yield higher XP.
Solo players require solo mobs and are only occasionally capable of a momentary flash of greatness. As an example, from time to time, I will draw aggro from a green heroic while soloing with my lvl 64 warden. Sometimes I win but even with the ability to self heal, most of the time, I lose and either have to eat the death or break the encounter. If the encounter is with blue or above, there is really not much chance at all.
Now, I know a lot of players on a lot of forums have laid claim to being able to take down heroic targets effortlessly but I think that for the most part, it's BS!
I think you need to adjust your perception of what is going to be enjoyable in this game. Your focus on wanting to play what someone else thinks is the "best scout" will not lead you to a rich gaming experience. No character is "best" in this game. All have strengths and weaknesses. Learning how to play your chosen class in spite of it's failings is what makes the game fun.
Bottom line here is play the class you think will best mesh with your playstyle and forget about being uber. If you become good at playing your character, uber will follow on it's own.
Regarding the classes you mentioned, Swashies and Brigands both do good damage.
As do Rangers and Assassins, with Assassins consistently leading in the T1 melee DPS race. However, it's doubtful whether any scout can out DPS a mage who is nuking full bore.