I may be wrong, but this may be one of the most successful preseasons I've ever seen.
I've played since the start of S6, though. This may also just be the preseason not settling yet. But I'm saying this because I don't think I've ever seen this many champs been viable at once. Say what you want about the new system being catered to new players, but the new runes system seems to have worked miracles in champion viability. I remember back when Champion type A was so strong, it forced all of Champion type B out of the meta entirely to the point where picking them was considered a troll pick.
True, certain champs aren't optimal but at least they're viable. And this feels pretty amazing to someone like me.