These are the factions that have been part of Teamfight Tactics for the most seasons and are always highly regarded.
Warriors (Seasons 1, 3, 3.5, 4, 4.5, 5, 5.5, 6)
The first name is a familiar faction for TFT players, especially those who prefer the 'meat shield' strategy. In all seasons, Warriors are trusted for providing a quality tank with synergy effects predominantly boosting health. With their inherent tankiness, Warriors only need about 1 or 2 defensive items to create formidable 'shield walls'.

Warriors have been consistently present from Season 1 to the current Season 6, with the only absence in Season 2. In some seasons, like 4 and 4.5 (with Warwick and Sett), Season 5 (with Sett, Nunu), Warriors are also a high-quality damage option. Effective compositions centered around Warriors as the main damage source, such as Warwick Grand Uncle Liandry's + Infinity Edge or the powerful Sett 'table clearer,' were highly favored by TFT players until these units faced significant nerfs.
Sorcerers/Mages (from Season 1 to Season 6)
For players who enjoy stunning and spectacular tactics, the Sorcerer/Mage lineup is a must-try. This lineup has been extremely familiar to TFT gamers as it has been a constant presence for 6 seasons. Particularly, Sorcerers/Mages always possess visually appealing, multi-target spells with devastating destructive power, contributing significantly to gamers' victories.

Some immensely powerful lineups revolve around Sorcerers/Mages, such as Ahri's 'one-shot all team' in season 4 or Vel'Koz's 'squid game' in seasons 5 and 5.5. In the current season 6, Lux is also an incredibly formidable name with multi-target skills that can penetrate any defensive lineup.
Assassins (from Season 1 to Season 6)
A powerhouse name that has persisted throughout 6 seasons, often being one of the most widely used metas in each season. For example, in season 5, LeBlanc became a 'nightmare' with the Infinity Edge - Hextech Gunblade - Guardian Angel combo. LeBlanc was so powerful that Riot kept nerfing her, eventually deciding to remove the champion entirely in season 5.5. Prior to that, in season 3, gamers became familiar with the incredibly elusive and board-clearing Shaco.

In the current season 6, Assassins also make an impact with at least 4 formidable names that can 'carry the team': Shaco, Katarina, Talon, and Ekko. These are all extremely strong names with both control and damage, making them difficult targets. Currently, the most effective Assassin lineup is the 6 Assassin - Gangplank setup. This lineup is rated as tier A with a win rate of up to 51%, with the top 1 rate being 10.3%.