Most Powerful Champions Lore-Wise (What I Think)
Okay, so I've been seeing lots of discussions all over the Internet talking about who the most powerful champions are (lore-wise of course) and I personally feel like a lot of these lists could maybe be changed in a couple different ways. But instead of being a jerk in the comments like some other people I saw commenting, I decided to make my own little list of who I think the most powerful champions are, lore-wise.
Just so nobody gets mad at me for not including every champ there is, I would like to say that I am NOT including every champion in the game on this list. I am just including the guys I see get tossed around on the other tier lists and champs who I think could potentially be very strong.
Now that that's done, let's get on to the list.
GODLIKE CHAMPIONS (the strongest class of champions on this list): (These are the candidates for the most powerful champion there is. These guys and the guys who are immortal, EXTREMELY powerful, can do things nobody else can, and if they can be killed, it must be VERY hard, maybe even IMPOSSIBLE to do so.)
Aurelion Sol (his icon wasn't released yet)
Kindred is LITERALLY DEATH. That automatically puts them in this tier. But they are also protectors of the life cycle and are nearly omnipresent! So yeah, they are, without a doubt, godlike. Bard is a dimension hopping, time traveling, protector of the multiverse. He is basically a guardian angel (Screw you, Kayle! Bard is the real angel here!). Aurelion Sol is a giant, cosmic, star forging/destroying dragon from space. If he can create and destroy entire STARS, he must have some godlike power.
BIOLOGICALLY IMMORTAL CHAMPIONS: (These guys are immortal, like the guys in the godlike tier, but they don't quite have the power that they have, and it is much easier to kill them rather than the guys in the godlike tier.)

These guys can live forever, and some of them do have incredible power, like Malphite. He has almost unlimited strength. Syndra has power that grows all the time. Morg and Kayle are part of an immortal race, Nasus, Renekton, Azir and Xerath each have great power, with Xerath being the strongest. Aatrox and Tahm Kench are demons, Zilean can control time to a degree, Lissandra has incredibly powerful ice powers, Anivia is the embodiment of winter, I think, Brand is a being of pure hatred and destruction, Nautilus lives forever, Skarner lives forever, Zac lives forever. EVERYONE LIVES FOREVER! So why aren't they in the godlike tier? Well, ask yourself. If this champion in the biologically immortal tier fought a champion in the godlike tier, would they survive? Probably not. As for Bard, he wouldn't even fight. It's not what he does.
Now we move into the other tiers of champions. I'm not ranking these guys from most powerful to least powerful anymore, because from here on out, I'm not quite sure who's stronger than who.
UNDEAD CHAMPIONS: (These guys managed to just barely escape death, and now they are immortal. But while they are immortal like the other guys in the godlike and biologically immortal tiers, their power is still quite limited.)

These guys have somehow managed to escape death, which is quite an amazing feat. But their amounts of power is generally smaller than that of the champions in the tiers before this one, they are still quite strong. Like, Thresh carries around a Pocket Prison wherever he goes, and that's pretty cool. But just because they escaped death once, doesn't mean they can always can. Some beings and weapons are capable of killing the undead with ease, like Lucian's guns for example.
LIFELESS CHAMPIONS: (Again, these guys are basically immortal. But, they don't quite have a soul. And being destroyed is the equivalent of being killed for them.)
and Full Machine 
These guys have immortality and a bit more durability than the guys in the undead tier, since they can still do lots of things with lots of wounds. And if they take too much damage, someone can repair them. But if their bodies are destroyed, or if someone takes out a key piece of them, they can shut down. For good. And you may be wondering why Urgot and Sion are here, when they are also in the undead tier. Basically these guys are part of two tiers. They came back from the dead, but, like the guys in the lifeless tier, they don't quite have a soul or free will.
STRONG BUT MORTAL CHAMPIONS: (These guys got skills. They can be strong, but these guys are the easiest to kill out of all the tiers, because they are mortal.)

A lot of these guys got some extremely powerful abilities. Some are strong, some are fast, some are great with magic, some are smart, some have great combat skills, some just want to watch the world burn (looking at you Teemo), you get the idea. HOWEVER. These guys are mortal, which makes them much easier to kill than the other guys.
UNKOWN: (Riot didn't give us enough info on the power that these champions hold, so this is the only place they truly belong.)

Some of these guys could be super strong. Some of these guys could be super smart. Some of these guys could belong in the biologically immortal tier. Do you see what word I am consistently using throughout these sentences? COULD. I am using the word COULD. You may be asking, why use the word COULD? Because I don't even know what tiers these guys belong in. Riot didn't give us enough info, so I can't put them into a tier without doubting myself a bit. For all we know, Gnar's Mega Form could put him in the biologically immortal tier. Maybe Rammus's ability to cause large earthquakes could put him into the biologically immortal tier. Who knows? And until we do know, we are keeping these champions here in the unknown tier.
So yeah. That's my list. I hope you agree with it. If you don't, feel free to post your suggestions in the comments. I might agree with you. But I might not. But there's always the possibility that I will!
So yeah, thanks for reading this long list.