The best BC is the one that fits you best and that you enjoy diving in. The Kailia has gotten very strong reviews and there are a lot of women who endorse it. If YOU prefer the Mares BC, then bless you and enjoy it!
I would recommend that you go weight integrated though. My first BC was not weight integrated and I found managing a weight belt to be a pain (on my hips!). It also had a tendency to slip, so I felt like I was constantly adjusting it. With the weight integration, I drop the weights in the pockets, zip them in and never think about them again until the diving is over.