I'm currently watching Cardcaptor Sakura (I KNOW I'M LATE SHHH) so I'm biased but the relationship between Sakura and Tomoyo is adorable. She loves and supports her a lot and even though Sakura probably doesn't fully realize, she also deeply cares for her. Another relationship I really like is the one between Nagisa and Honoka in Futari wa Pretty Cure. These girls have different personalities, different hobbies, talents and lifestyles but understand each other perfectly while fighting as Precures.