This is without the hotfix. I will make a 2nd post with the hotfix data once we had enough time with it and try to make it very long.

Items:

• AP (no mana): Many of them do too well. Riftmaker, Stormsurge (Hotfixed), Liandrys, Nashors, Lichbane, Zhonyas, DC. But there are also balanced ones like VS, Cryptbloom (I call it Crypto Bloom), Morello, Banshees, Shadowflame, Horizon and Cosmic.
• AP mana: Every AP item that also gives mana is mostly balanced except for maybe Malignance (the MPen) and a huge maybe on ROA.
• Marksman: They seem to mostly do fine. Not much better or worse. Their items are mostly fine except for Collector (hotfixed, could still be OP). Their overall item power is even or up if we ignore the removal of the mythic passive stats. Especially PD gets underestimated right now.
• Bruiser/Skirmisher: Sundered Sky is the best item there right now, mostly in the 1st or 2nd slot. Trinity is 2nd in terms of strength but often still better rushed. Most items do fine but not as good as these 2. Stride was weak before the hotfix. Hull is now very niche.
• Lethality: These items also do fine. Maybe a bit too good on ADCs due to the change of Lethality not requiring lvls anymore for the full power.
• Tank: Most items here are also fine. MR items maybe a bit too good (hello Rookern) while Heartsteel underperforms (hotfixed). Trailblazer does well but overall support items are harder to evaluate.
• Enchanters/Catchers: Many items there are strong but people still build the old mythics early instead of going for stronger laning items. Especially Imperial Mandate and Ardent/Flowing Water are very strong rush items. The old Mythics make more sense in the 2nd slot now except for Moonstone on Soraka.

Champs:

• AP bruiser/assassin: AP assassins and AP bruisers are doing insanely well. That is why they got hotfix nerfed mostly. For some reason Riot missed Morde.
• Mages: Mages do overall really well. Many could do better with more optimized item builds, but they are often strong and rarely weak (Lux buff was for support not mid). Ahri is pretty much the only slightly lacking mage right now.
• Marksman: Aside from Aphelios who already got a small hotfix nerf most ADCs are fine. MF and Nilah are too high and should get nerfed soon. Ez already got hotfix buffed.
• Bruiser/Skirmisher: Here the results are very mixed, but like with mages, there is a lot of opimization potnetial for many of the weaker looking bruisers. Garen looks like 45% WR but his actual WR with optimal items is close to 49%. The 3 brusiers who are really trash are Illaoi and maybe Renekton. Garen, Darius, Shyvana and co are still slightly weak.
• AD Assassins: Most AD assassins are ok. Noc is on the stronger side, Rengar, Qiyana and Talon fine. Kha and Kayn slightly weak. Zed already got a hotfix buff
• Tanks and very tanky bruisers: Most of them are fine top and strong as supports. Riot did the overall best job here. Zac already got help and maybe Sion needs a tick of power but nothing that has to be done in the next weeks.
• Enchanters/Catchers: Many Enchanters are doing fine and could do even better with the right item builds. Even Karma with Imperial + Ardent would get out of the worst slump. Catchers like Blitz, Rakan and Bard are insane right now.

I use Plat+ data as default

Champ Data: % PR increases are +-% numbers with the last patch being the base line. I do this because a 1->2% has a larger impact than a 10->11% PR change.

• e.g.: 2% -> 5% = +150% (2.5 times as high as before)

Item Data: Below each item you then find all champs using that item in that slot. The data below the champ picture is the AVG item WR of that slot for that champ. Next to that you find the item data for that champ with the curreent data.
Links: Champ icons are links to LOL WikiThe role next to the icon is a link to LoLalytics