Whether a girl prefers fingers or toys when they masturbate usually comes down to personal preference, the specific sensation they are craving in the moment, and what they are trying to achieve. Many women enjoy a mix of both, as they offer very different types of stimulation.
Many prefer fingers because of the intimacy and precision. Fingers allow for a level of tactile feedback that toys can't match; a woman can feel exactly how her body is reacting and adjust the pressure, angle, and speed instantly.
Fingers can easily switch between clitoral rubbing, inserting into the pussy, or teasing the entrance. The ability to use a thumb for the clit while fingers penetrate the vagina allows for simultaneous stimulation that feels more natural
Toys are generally preferred when the goal is intensity and efficiency.
Vibration is the biggest draw. A high-powered vibrator provides a level of consistent, rapid stimulation that human fingers simply cannot replicate. For many women, vibration is the most reliable way to reach a powerful orgasm.
Toys don't get tired. A vibrator can maintain the exact same rhythm and intensity for as long as needed. Toys also offer variety, from G-spot curved vibrators to suction toys that mimic oral sex, they can target specific nerve endings with a precision and power that fingers can't reach.
In many cases, the favoured method is a combination. A common scenario is using fingers to build up arousal and lubrication, then switching to a toy to push the climax over the edge.