Back in the day, soaps knew how to set up complex rivalries that wasn't always about a man. Viki/Dorian from one life to live and Katherine/Jill were the best soap rivalries, followed by Brooke/Erica from all my children, the Natalie/Erica rivalry had some teeth as well.. Sami/Nicole could have been better but they were the best rivalry during their era, plus, you have both ladies who were on the same level morally. It was not a standard good girl/bad girl with the good girl winning all the time. Both Sami and Nicole have done despicable things to others for their selfish reasons. The funny thing with Sami and Nicole is that Sami genuinely liked Nicole until Nicole betrayed her. Nicole seems to have a thing about wanting those closest to Sami, first her brother, EJ, her ex Lucas, Will (Yes, I know she married Lucas for money but it was also to get Will away from Sami in favor of Lucas) and finally her daughter Sydney. With better complex writing, they could have been on the same level as Viki/Dorian..