I would say Otto Hightower fits for me, but of course he isn't around at the moment. He's about as close as we'll get to a Tywin Lannister type character in this show.
Viserys was a good character and a great performance, but he's long gone.
I can't fault Emma D'Arcy or Olivia Cooke, their performances are both impeccable. The story and its pacing is what makes their characters suffer.
Rhaenys was probably the best character remaining in the show, but also gone.
Daemon could be an amazing character if they tried. He was great in season 1, but forgettable this season.
Larys Strong started out really interesting but his character hasn't evolved much at all and has only gotten more dull.
Aemond could have been a great character but he really only hits one note. Being an angry, overcompensating little bitch driving around a big truck only works if you act like a normal person at least some of the time.
Mysaria could be close to as cool as Varys but they don't give her anything to do or any real screen time.
Criston Cole is easy to hate, but also boring. He doesn't do anything but act like a tool and whine. Like Aemond, no character depth, completely one note, despite the little speech they gave him in this episode.
I think the main problem is there are just too many characters to flesh out in a show they're cobbling together from really thin source material. The true irony is it feels like they're milking it for all it's worth, and yet the timeline is sped up and too much is skimmed over to let us get to know any character really.