(Demon, and Phantom for sure, but "Sorcery maybe" because Sorcery can be overpowering, Thresh perhaps shouldn't get Sorcery Champ Comp...)
Thresh because we need someone to handle the Corner Main Campers, to counter Glacial's, and to save champions from AOE powers like Brand has. Thresh can pull opponents from the far corners, stun them for 0.3 seconds, resetting their mana and passives, so champs like Draven can't continue to destroy champions like a cake walk from hiding in the corner. Thresh can be "Phantom" to add more Phantom Variety, "Demon" to mana burn, and "optionally Sorcery" to grant some spell damage bonus. Countering Glacial's requires burning their mana, so making Thresh a Demon would help make him an effective counter to the current meta. Phantom would allow him to weaken a Glacial by lowering their hp for an easy kill at the start, against Glacial champs like Sejuani, Volibear, or Braum. Sorcery would just help his ability to damage from basic attacks or his pull ability. Thresh's passive can be teleporting the weakest "Ally Champions" distant from their current location in danger, to save them from threats such as overwhelming AOE powers from Brand.
Thresh should likely cost around 3-4 gold for near mid, to exactly mid game arrival in the deck to draw, so players can start to counter the meta before the meta player just takes off with dominant power. As Thresh will need his items and Tier build up before it's to late. Thresh at the least should cost 2 gold, and can show up around phase 2 or 3, and at latest being phase 4 for deck arrival to draw Thresh.
Thresh would need to be fairly ranged with the basic attacks, but not like a gunslinger or ranger, but similar to the spider, Elise. If the troop is not a gunslinger or ranger, they certainly should not be capable of fighting from the corner, even with a Rapid Fire Cannon that Corner Campers use.
In this way, I feel we need Thresh as soon as possible! We need champs that can guarantee mana resetting opponents, and their passives. So Thresh seems like the ultimate champ for the task. Thresh has to be good even as a solo champion without Champ Comp, so that he can be a solid counter against the meta, for those who want to enjoy variety.
"Thresh in this case would be a major middle finger to the meta, and for those who want to get creative with their setup, instead of copy pasting a setup everyone else seems to use, to a point of absolute boredom!"