I love going solo top with Nasus. Keep farming that Q whenever you can, get a tanky setup and you can easily lead your team to victory, though I am not sure he is viable in ranked games. :/
As for mid, I really like playing Anivia for her stun and her wall can seriously hurt your enemies.
I don't play ranked games, but I think Anivia should be a pretty good champion for ranked games.
I may be wrong, but I just want to point out that Morde might not be the best choice, since he has no CC, nor does he have any escape mechanism, which is realllly annoying.