Not Classic Tetris, but Tetris 99[1] and the Tetris: The Grand Master series[2] are also worth checking out if you are into competitive Tetris.
Tetris The Grand Master has actually been part of The CTWC for a few years. My favorite is from CTWC 2017, one of the craziest finals in Tetris ever. Round one starts here: https://www.youtube.com/watch?v=a0xTEkejOtI