It's fast, there is not a lot of farming required, losing only takes up 7 or 8 minutes, comebacks are always possible.
And honestly, I only play normals and I have seen a huge variety of champs. Of the last 10 matches or so, I think there was 2 jaxes, a rammus (who went bot with ali and held both bottom points the whole game), and a few GPs (free this week). The only champs I have never seen: Annie, Corki, Gragas, Janna, and Swain. I have seen every single other champ at least once, most of them several times.