Unpopular Opinion: Riot has done a pretty good job of balancing TFT STrategies

Below are just a few of the complaint threads about various strategies. Between even just these strategies, most champions in the roster can play a valuable role. That's pretty damn good considering there are 54 champions in the rotation right now.

Glacial is too strong: https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/11gt6Vke-glacial-is-busted-needs-small-nerfs

Assassins are too strong: https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/wAxlvuBZ-every-team-is-assassins-or-volibear-can-we-get-like-a-weekly-tft-ballance-check

Volibear is too strong: https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/wAxlvuBZ-every-team-is-assassins-or-volibear-can-we-get-like-a-weekly-tft-ballance-check

Gunslinger is too strong (Okay this one is more about an item): https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/PKsNhsjG-cursed-blade-can-reduce-four-levels

Yordles are too strong (Also mentions glacial and assassin): https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/eEW4WpsB-soooo-why-use-anything-other-than-yordles-glacial-or-assassins

Ninjas are too strong (Also mentions Assassins): https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/E0oEwq3y-ninja4-assassin6-is-way-too-strong

Demons are too strong: https://boards.na.leagueoflegends.com/en/c/teamfight-tactics/4LXZur14-demon-mana-burn-is-absurd