Need General Knowledge About Hard Carries

I've recently played a lot of Juggernaut, and I have to say I really like him. He is fairly easy to play and has a good presence all game long. Insane damage and heal, as well as a free BKB. But he is fairly squishy.

Okay so I'm your expert here, having played every hard carry in the game at one point or another.

Troll Warlord and Outworld Devourer are not hard carries, merely extremely strong midgame carries that scale well into lategame like Shadow Fiend and Doom. In rough order, hardest carries are:

1. Faceless Void. He has a permabash ability which deals magical damage (ie not reduced by armour), 25% damage dodge which gets progressively more annoying as the game goes on, mobility in Time Walk and a full five seconds of beating faces with no repurcussions.
2. Medusa. Absolute potato and quite possibly my least favourite Hero but god help you if you're against a fat Medusa. AoE monster with Split Shot, possibly the second-highest EHP in the game. Downside is, she's really slow. And really boring. Like, really boring.
3. Spectre. Highest EHP in the game by far (it's about 12000 when 6-slotted), and 22% of that will be dealt to you. If she has 4000HP, you deal 4k damage to her, 800 is reflected, and Spectre's STILL alive. Then she pops Satanic and you have no idea what to do. Desolate and Haunt also deal tons of damage. Three scaling abilities makes Spectre easily on par with Void and Medusa.
4. Terrorblade. The illusion Heroes are generally close together, and while Terrorblade's 120% damage increase from Conjure Image isn't as much as the 160% of Juxtapose the Demon Marauder's base damage is much higher. Also got three scaling abilities which make him progressively harder to deal with the longer you let him farm.
5. Morphling. His carry potential comes not so much from the shotgun as from his powerful, consistent right-clicks, his Manta Style illusions, and from the fact that if you focus him he'll morph Strength and you will have a really hard time killing him.
6. Chaos Knight. 300% crit AND a potential 400% extra damage in illusions? Yep. The downside is he's a Strength Hero who is limited by the fact that he isn't Agility.
7. Phantom Lancer. Every ability has something will illusions. As you may have guessed, illusions are pretty much guaranteed to make you a hard carry.
8. Tiny. He's technically an illusion Hero with his massive base damage and his building of Manta Style, but his damage on his own is also massive. Craggy Exterior makes him extremely difficult to take down and gives him durability even beyond his natural HP.
9. Gyrocopter. Similar to Medusa, but he deals slightly more damage. However, it's only for 6 hits and he's really squishy, which limits his hard carry-ness.
10. Lone Druid. Contrary to popular belief, after 60 minutes the Druid actually falls off, mainly due to the fact that his bear's HP doesn't increase. At the hyper-lategame where the likes of Void and Spectre thrive, the bear dies very quickly, even with a BKB. Before then, though, the Druid will slaughter with impunity.
11. Luna. Moon Glaives tears apart teams and while that is her only scaling ability the fact that Manta Illusions get the passive makes her somewhat an illusion Hero, despite that she doesn't build stats. Also makes a cool noise when you attack something.
12. Naga Siren. She's the weakest fighter of the illusion Heroes, due to many nerfs to Mirror Image. The problem with her is that everything she does Terrorblade can also do, with the exception of her ult. Still powerful lategame though, but won't stand up to as much.
13. Alchemist. He's an awkward Hero, because he only has one combat-orientated carry ability (even Weaver has two-and-a-half). However, his insane attack speed and regen allows him to melt pretty much everything he sees... if he can get the attacks off.
14. Tinker. I reserve a personal hatred for playing against Tinkers and it's a sure way to assure a Doom pick. Permahex is as dumb as it sounds.
15. Anti-Mage. Second only to Medusa for the Hero I find most boring to play. He hard carries by farming incredibly fast and being 6-slotted 20-30 minutes before even Terrorblade. The downside to this is that he has a 15-20 minute window where you NEED to win before he gets outcarried, as Mana Break doesn't scale very well into the ultra lategame and neither do his Manta illusions.
16. Phantom Assassin. Despite the fact that her damage steroid crit only offers a mere 50% increase to damage on average, she scales well into the lategame with massive physical burst and an absolute inability to be kited like Lifestealer. She excels at 1v1ing carries and lone supports, but won't carry a team as hard as someone like Gyro or Luna can.

As for your questions:

Troll Warlord
1. His lack of popularity isn't because he's weak. He's just like Tusk, in that he's overlooked for whatever reason.
2. Hell no. If you give a Troll 30 seconds in your base you lose a rax. He is, however, limited by kiting and crippling single-target focus.
3. Not too hard. He suffers the 'Lifestealer syndrome' in that he hurts if you let him whack you but buy a force staff/ghost sceptre and just kite him. Lategame he can't deal with hard carries, they'll kill his team and 5v1 him.

Medusa
1. Her midgame is bad because she has very little damage, no disable, no ganking ability, is slow and generally useless at everything except farming.
2. Preeeeety much impossible. It's really close between her, Spectre and Void as to who can carry the hardest, and generally depends on who farms the faster.
3. Imagine a brick the size of Uzbekhistan. Drop that on your foot. That's how hard she can carry.
4. I can't speak for other people, but Medusa for me is slow, doesn't come online until I fall asleep, farming with her is boring, no midgame, no earlygame, absolute vegetable, needs Rapiers to deal real damage, takes 3 5k gold items to not feed, and is repetitive to play with and against.

Anti-Mage
1. Why do people like Nature's? It's because having dosh is fun. Other people are better to ask than me on this one, I hate Anti-Mage.
2. He falls off super-hard, so not very.
3. See above.

Spectre
1. Dispersion is not weak. Lategame, that one ability will deal half of a support's HP as damage, and that isn't even counting anything else.
2. Her lane isn't honestly as bad as people say. It's REALLY bad, but if you can catch someone alone you hit like a truck with Desolate.
3. You can't kill her :)
4. See Medusa.
5. They don't? It's frustrating to play against a good Spectre but (for me at least and I have ~50 games with her) she's very fun to play, since you can snowball hard off a midgame instead of AFK farm with a Radiance.

Faceless Void
1. He's a 'playmaker' like Pudge. A good Chronosphere can completely change a game and pulling off a 5-man chrono into teamwiping your foes gives a massive rush.
2. If he chronos you, you can't. If he doesn't you can try and kite him but he still can Time Walk.
3. A bit. He's not great without his ult but 6-slotted Void doesn't care about ult that much if he has a BKB. Problem is, everybody does this stupid Mask of Madness and never farms. Please go Midas into Mjollnir >_<

Outweed Dankvourer
1. As someone else says, depends on the mid. He wins mid really easily against a lot of Heroes. If you feel confident in a 1v1 situation over a 2v2 or 3v3 situation then go mid. Adjust according to game.
2. He isn't a hard carry, so it's not too hard. Fortunately, you can't kite him because he'll generally build Rod of Atos.
3. Use Astral Imprisonment to interrupt enemy last hitting and denying. See them going for it? Nope, then take the creep.

Hopefully I could help. If you want, I'll post a detailed explanation of how the carries scale, what scales about them, etc.

I think I ahould say that when I ask why do people like AM so much, I was referring to general scrubs... does mana break attracts scrubs?

Well TBH I did see one with Desolator and deadulus, only viable in pubstomps ( I was in that pub and the team that lost )

They're attracted to Blink actually, that stuff makes people "high". I personally played AM in pubs a year ago(was a noob) just for that single ability.

Carry Dazzle = pubstomp. Yes he has reasonable primary stat gain and agility, but no, he has nothing else that helps him carry directly - i.e. things like Shallow Grave and Weave can apply to other heroes too. Not a great main carry at all.

AM - peaks a lot sooner than any other hard carry (a good start and enemy feeding not withstanding). One of the hardest carries to gank if you don't have the right heroes/items. Also, Mana Break is very effective against other specific heroes - ones with big pools like Pugna, Skywrath Mage and Enigma can be exploded to great effect - but more importantly, Medusa and Wraith King can also suffer a lot against him and 3 x Mana Break (from illusions).