I just started playing TFT again and I have a decent understanding of the meta. I'm reasonably confident these comps are pretty close to optimal, other than Dark Stars, but I have no idea how to position.
More positioning memes coming soon™. Until then, please take these positionings with a grain of salt.
Five Costs
This is the optimal version of the comp, but I have no idea how to get here. From what I've deduced, it seems like you go either Astro Snipers or Dark Stars and slowly transition into this comp. You really need Aurelion Sol two, but everything else you can probably calmly roll in to.
Astro Snipers
I haven't had too much success with this comp, mainly because of positioning I think. After watching a few streams, I think this might be good positioning for Teemo, but I'm unsure.
Lulu is more important than Karma level eight, then go nine and throw her in. Be careful where you position Gnar as he doesn't ult as easily as you'd think.
Cybernetics
Surprisingly this comp has made a resurgence. Maybe because of the recent Lucian and Vayne buffs on top of the Irelia buff a few patches ago.
Throw an Item on Lucian early, ideally a Rod, stack Vayne when you find her, get a big item on Riven eventually, go nine and throw in the good ol' Thresh, Urgot combo.
Also, it's highly recommended to go Infil Spat on Irelia, if not, a defensive item is fine, preferably Frozen Heart since she dashes to the backline.
Blademasters
I have no idea what I'm doing :).
Mech Sorc
Not much to say here. Roll at six a bit, roll at seven a bit, go eight, temp Ziggs until you find GP, then possibly throw in Thresh, Urgot at nine if the game is still going.
I played a weird variant of the comp yesterday and it seems good. Consider going this in Dwarf Galaxy.
Dark Stars
I would say this is the only comp I'm confident on, other than if Shaco is supposed to be played or not.
The problem with the comp is its early game sucks, so try to go Vanguard with a DPS and slowly transition into Protectors. Also, if you have Shojin on Ashe early, it's a first. You can also play Shojin Bard with the comp and fast eight.
As stated with Five Costs, I think this comp transitions into it, but I'm unsure. Throw in Urgot level nine if you can get there by the way, but you can still top four at level eight.
Egirls
Stack Syndra, then stack Xerath. GG.
Blaster Brawler
Giant Slayer is a crank on Jinx. Just get a bunch of Bows and Swords and you're good to go.
I have no idea what you throw in at nine, so good luck on figuring that out!
Meta Update
The meta update will be back a week after my patch notes as I didn't make too many predictions last patch, and the ones I did were a grief.