Initial thoughts on the reworks:
Graves: Hits rly hard, destroys towers insanely fast, pushes quickly, but csing may be awkward. He autoattacks twice, reloads (gives full ammo if he runs out), and autoattacks twice again. Don't rly have an opinion since his rework is so drastic, but I think he'll still be viable bot despite the massive range loss. PBE doesn't seem to properly show his passive's damage output when he crits, however.
Corki: Now deals 25% physical, 75% magic; his passive does not change Triforce's damage to half magic. Anyways, this thing might be broken. Triforce + Reaver granting 40% cdr and his new focus on magic dmg makes Void Staff an appealing option, which now buffs everything Corki has instead of just half of his kit. Ult damage has been changed from 260 (+40% total AD) to 180 (+80% total AD) at level 16, so it hurts more now (deals around 500/750). So now, with 4.8s recharge time, 20 mana cost, 2s cooldown rockets that actually hurt since you can itemize for it, along with the fact that this rocketspam corki can now fight with autoattacks (compare with old AP corki who had to sacrifice autoattack dmg, and old AD/standard corki who couldnt itemize deep into magic pen to amp his poke lategame), he should be really scary. Then there's the whole AP nerfs/ad buffs so double AD + corki comps could make a strong return.
Triforce/Essence Reaver/IE/Scimitar/Sorcs/Void
Lucian: No rework here but being able to build 40%cdr without feeling awkward is really nice. Same build as above except with armor pen instead and obv not sorcs.
Kog'Maw: Havent checked W's scaling but they really want you to build Bork Hurricane on this I think.
Jinx: Despite the 15% AS nerf on rockets, the fact that Hurricane can crit could be really scary on this champ...