Three Strongest Decks
According to Balco & Legna, these are the strongest decks at Plat+ (all three hovering at 55% WR), when you consider decks with a playrate over 1% at Platinum and above:
Yuumi Pantheon Demacia:
Attached to the feline Fae, Pantheon reaches the summit. Adding one copy of Chain Vest and one copy of Gift from Beyond seems like a great idea, while cutting Bastion and Hush:
This archetype is solid into pretty much anything except Gnar Ziggs, Gnar Swain and Elise Noxus (aka spiders). Works very well against Scouts.
As an alternative, there's a similar version including one copy of Taric while swapping one Yummi out.
Scouts
Arguably the safest best to climb the ladder — this thing works, works well, and has been working well for weeks.
It has an awful time against Yuumi Pantheon (which probably explains while we find those at the top), but it's even or favored into mostly every other popular archetype.
Teemo Tristana Gnar
Still fascinating times to be around — while we no longer have a Timelines deck at the top, we do have a Tristana build!
Having taken the ladder by storm last week, this Fae flood has proven to be no fluke, and it has a fairly fair matchup spread: it has decent odds (between 45% and 55%) against pretty much everything.
Two Less-Played Options
If you want something with a lot of punch, but little-seen on the ladder, here are two options.
Elise Kindred Vi
If the top three options are a tad too midrange-y, here's a deck leaning a bit more towards the Control end of the spectrum — not to mention, you get to play Kindred! =)
This archetype sees play mostly in the EU shard; if you take it for a spin in the Americas or APAC ladder, odds of finding yourself in a mirror are very low indeed —it's very weak against Darkness, Yuumi Pantheon and Teemo Tristana Gnar, so keep that in mind.
Lucian Zed
Sometimes dubbed "Bangbros", here's a Demacia deck with a lot of punch that doesn't run out of steam thanks to Sai'nen Thousand-Tails. It's mostly seen in the European shard.
Not ideal against Tristana & friends, and a bit weak into Scouts, but solid performance overall.