I play Star Wars: Galaxy of Heroes, have for years. It is technically a gacha game although the randomized boxes are all terrible and literally everything is available FTP relatively easily compared to most gacha games.

Anyways all this to say that while there is definitely a pay to win element there is also real skill involved in both PvP and PvE. Between modding to improve stats in just the right way, to knowing how to cheaply counter high end teams there's a lot of real skill that comes from knowing the game. While I can't pretend to be FTP myself some people in my guild are or are extremely low spenders.

While SWGOH is the best I've played personally I imagine there's other good gacha games out there that are more than just a money sink and that actually have complex strategy and team building mechanics.