One big reason why I will miss Twisted Treeline
Occasionally I didn't like queueing up for a 5v5 because I would be convinced that the game with 10 people will be too stressful, everyone judging every single thing you do or won't do. A game where every second feels like it can be game changing..
TT has managed to be the complete opposite of all that, it's a chill place to play and it's now going away.