idk, I'm not a huge Katherine fan tbh, but this season's Elena has been irking me. I think it's because while Katherine is manipulative and bitchy, she's not shy about it. She knows it, she embraces it and she's proud of it. But this season, Elena's been manipulative and ~bitchy (I say this in this way because I don't think she's trying to be, but she has been coming across as really insensitive to other people's feelings and thoughts, or only being compassionate when it serves her positively), but the thing is, Elena's trying to come across as a martyr or saviour. But she's not. If anything, she's just being annoying, imo.
I think though, the downward spiral in Elena's character is the writers fault. They're trying to prop up the triangle but they're handling it wrong. They didn't have to make Elena Katherine-lite to do it. Could've been handled much better. *shrugs* I know the triangle is important, but I just do not like the way it's being handled and the way all three characters are being massacred to do it.
I still prefer Elena > Katherine though. I like Katherine as this fourth angle who only thinks she's important, but isn't really. lol.