If there's anything I've learned from watching this show it's that anyone who lives long enough will eventually commit an "evil" or morally questionable act at some point. It's the nature of their world. But Cersei's been the evilest of Evil Queens since the show began imo. There's a reason The Mountain, well known for his cruelty, is her closest companion aside from Jaime. I mean she's one of my favorite characters and I love to watch her but I really don't think there's any good in her.
Dany is just as ambitious and power hungry as Cersei, but I've always thought she has a good heart and tries to treat people fairly and with respect. Her sense of justice may seem harsher than necessary at times, but I think she genuinely wants to do the right thing and be a good ruler. Does wanting to be a good Queen make her a good Queen? Not necessarily, but I think she could get there, especially with people at her side like Tyrion. Honestly, since I started watching the show one of the things I've wanted the most is to see her sit on the Iron Throne. Is it predictable, yeah, but for some reason I just want it for her. I've enjoyed watching her rise from nothing, growing in confidence and strength. This is the first season I've posted here, so I've been kinda surprised to see that a good amount of people don't seem to like her. lol
Cersei doesn't care about or respect anyone but Cersei. She may have loved her children in her own way, but her actions with Tommen proved that she will always put her own desires and well-being over everyone and everything else. Catelyn Stark, for example, would've gladly fallen on her own sword for the sake of her children's happiness, but Cersei refused to let Tommen make a choice that would back her into a corner. Anyway, Oberyn's story about when he met Cersei after Tyrion's birth told me all I needed to know about her. She's been selfish and cruel almost her entire life.