Not a single one of those "third party products" are actual fantasy leagues...
Can we NEVER let Riot try to pretend they give a f**k about Fantasy ever again? They've just been lying right to our face for years, and it's really getting pathetic at this point.
EsportsOne is pretty close to the old fantasy league - season long fantasy leagues where you have to be organized by your friends and you can only enter at the start of the season don't work well (we know that from our own data). The others are not fantasy leagues, but hit different audiences.