When choosing a G-spot or P-spot dildo, consider the following factors: 

1. Size and shape: G-spot dildos are typically curved to help target the front wall of the vagina, while P-spot dildos are often curved to reach the prostate gland. Consider the size and shape of the dildo to ensure that it will be comfortable and practical for your body. 
2. Material: G-spot and P-spot dildos can be made from various materials, including silicone, glass, and metal. Choose a material that is body-safe and easy to clean. 
3. Texture: Some G-spot and P-spot dildos may have added texture or ridges to enhance stimulation. Consider whether you enjoy textured stimulation when choosing a dildo. 
4. Vibrations: Some G-spot and P-spot dildos may have added vibrations to enhance stimulation. Consider whether you enjoy vibration and whether or not you want a dildo with this feature.
5. Budget: G-spot and P-spot dildos can vary in price, so consider your budget when choosing a dildo. 
6. Brand and reviews: Look for reputable brands that produce high-quality G-spot and P-spot dildos, and read reviews from other users to get a sense of the dildo's effectiveness and overall quality. Ultimately, the best G-spot or P-spot dildo for you depends on your preferences and needs. By considering the factors above, you can choose a dildo that is comfortable, effective, and enjoyable for you to use.