OK, let me give this a shot by contributing a primer on one of the most dumped upon classic five-stars - The Mighty Thorne. (@Muchacho is not at all surprised that this was who I chose for my first pass.)
First of all, Thorne’s artwork is some of the coolest in the game, I think. He just has this look like he’s seen things. Kind of that Jack Nicholson “you want me on that wall” stuff. And his special skill has an awesome name too - the Icecold Finisher. So Thorne exudes cool.
The reason people dump on Thorne is because his special only does one thing, which is hit hard. It’s called Icecold Finisher for a reason - if it doesn’t finish whoever it hits, it doesn’t do anything else. And I’m not gonna deny that sucks. But it does hit pretty hard. And if you can mix it with some attack up and defense down, it hits REALLY hard. And knowing this is the key to making the best use of Thorne.
You see, Thorne has tanky stats. Like, really tanky stats. And he’s a paladin, which makes him even tankier. So you look at him, and you go, “Well, he’s gotta be a good tank.” And that, I believe, is your first mistake. Past a certain point, at least, Thorne is not a good tank. In fact, I feel like Thorne is not really good on defense at all. Because if you can’t time and target his special, it doesn’t do what it is supposed to do. (Icecold Finisher, remember?) As much as I like Thorne, I do not fear seeing Thorne on the opponent’s defense team. Like, at all. Ever. I kind of relish it, and I usually don’t even stack against him. So, first point, Thorne has defensive stats, but he doesn’t really work that well on defense. Got it? OK. Let’s move on.
Thorne’s job is to hit hard, which is why you want him on offense. Because offense is about hitting hard. And because you can time and target his special correctly. Another thing people don’t like about Thorne is that he is average speed. But you know who else is average speed? Kiril and Grimm. And you know what makes Thorne hit really freakin’ hard? Getting Kiril’s attack buff and Grimm’s defense down against the same three heroes Thorne is about to hit… HARD. Because that’s what Thorne does. If you raid 3-2, this 3tack of Kiril, Grimm, and Thorne is a pretty effective one for wiping out the opponent’s center, or one side of their defense. It’s also straight-up brutal on mob waves with three moblings, or triple bosses.
Now, if you’re lucky enough to have a special hero with elemental defense down (i.e. Frida or King Arthur), then I’m guessing Thorne’s damage just gets stupid high. I’m guessing because I don’t have either of those two. But trust me, I’m pretty sure it would be awesome.
Another way I like to use Thorne is in conjunction with Gormek and Brynhild, which is kind of a weird team-up, but it works for me in wars, where I usually go rainbow to make sure I don’t drain my bench of one color too early. I like this combo because Gormek is a giant pile of meat himself, so both he and Thorne survive pretty well. And with a fast healer like Brynhild in the middle of them, they survive really well. And Brynhild boosts their mana generation, which for two average heroes is nice. I know they are all different colors, but did you know Gormek’s defense down lasts six turns? SIX! That’s a long dang time! So you don’t have to have him and Thorne ready together. You just have to fire Gormek, and Thorne can usually take his sweet time about getting ready to fire. You still get the same punishing hit-three effect. You could also try this with Kasshrek (with or without costume), I guess, but you wouldn’t get the mana boost.
Finally, if you are going to emblem Thorne, I suggest doing it along the attack path. Now, first of all, the forum is going to mock you for embleming Thorne. Because they hate Thorne. Because he’s average mana, has no secondary effects, and requires other heroes alongside him to do maximum damage. But you’re going to use Thorne, and you’re going to use Thorne to great effect, because you are a vanilla hero warrior, and that’s what you do. (No one else is stupid enough to still be reading at this point, right?) So you’re going to emblem Thorne, and you’re going to emblem him along the attack path. Even though he has tanky stats. Even though he’s a paladin. Because Thorne hits hard. It’s all he does. So you need him to hit harder. Got it? The tanky stats are a bonus, because it usually means he lives long enough to hit hard.
So, we’re not pretending Thorne is Gravemaker or anything. But we’re not pretending he’s garbage, either. Because now we know better. He’s not a defensive hero. He’s an offensive hero who lives long enough to hit hard. There you have it - The Mighty Thorne, as told by Noble Weasel.
(BTW, his costume isn’t out yet, but I hope to get it and update this post accordingly once I do.)
Vanilla heroes aren’t as flashy but they are a staple and too many people underestimate what they can do! Also some of them that don’t seem great at first site actually really shine with emblems - Elk is one example. His attack stat is low which makes his special seem ineffective but if you boost it with emblems he can literally become a one man army. The benefit of having less hero choices in one’s roster is there’s less competition for materials and emblems. 
. Let’s face it, even if we use all these we do have favorites