I'm more saying anything much here but I'll just give a bit more detail on Morde (huehuehue #1 sorry had to say it) since Ryu is a lot more well-known. Morde is a lot tougher than just someone with a metal mace and shrapnel flying around with a curse. I'll use game mechanics to justify things since there are no cutscenes or anything to go by in League of Legends (LoL) since it's gameplay. I know game mechanics aren't proper indicators but it's the best there is for League of Legends
For one thing, he might not even be a person, he might be a soul in armor, he might be an undead thing, who knows. He is a lot weaker in the game because in League of Legends lore all summoned champions are bound by the magic that allows them to fight at roughly equal levels for political stability of the world. This means that someone like Anivia in LoL who is basically a powerful ice phoenix made of pure essence of another world and "can not die and has seen the world renewed several times" can face lesser people like Garen who is merely a really good general on equal terms.
Mordekaiser can inflict disease really easy and he is fairly tough to take down due to his shield which powers itself when Mordekaiser hits an enemy with a spell, more enemies hit means more shield. He has dealt with other great fighters too who can wield melee weapons exceptionally well. Mordekaiser has dealt with powerful magic such as Malzahar with the power of the void and can open portals to the void dealing constant damage or just flat out crush someone and suppress them in a void (this move can only be stopped if you're not in range), Kassadin who can riftwalk, Kennen who can summon a lightning storm around him, etc. Physical combatants like Garen who strikes so fast with his signature move that it looks like a sword dropped on someone (but as confirmed in an interview it was a series of slashes so fast it simply just looked like a giant sword dropped on someone) and Jax who is simply so powerful and skilled as a weaponmaster that he caused a worldwide political imbalance by winning so much and so easily that they sanctioned unique rules to nerf him. Jax basically said ok and nerfed himself more by restricting himself to only using a lamppost to fight and he's still winning.
Gamplay-wise, 1v1 Mordekaiser can beat Anivia (by dodging her stun and standing out of her instant icestorm and beating her with spells) and Kennen (shield generation, nuke him, ultimate to life steal) and Jax in the early going (after a while, Jax becomes almost unbeatable 1v1 in LoL though). Garen in gameplay is about even since Garen can burst through the shield and finish with his ultimate but a longer fight between Garen and Morde will have Morde winning.
I'm not voting for either side but I'd thought I'd give insight into Mordekaiser since even if people vote Ryu, I don't want it to just be that they voted for Ryu because they have no idea what Mordekaiser is
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What the heck is that?!
IN-DIG-NAY-SHUN!!!!!