Choosing a signature asana after 30 years of practice depends greatly on your personal preferences, body type, strengths, and areas of focus within your practice. However, here are a few iconic asanas that practitioners often gravitate towards after years of dedicated practice:

1. **Sirsasana (Headstand)**: This inversion requires strength, balance, and concentration. It’s often considered the king of asanas and can be a culmination of years of practice.

2. **Padmasana (Lotus Pose)**: Known for its association with meditation and spiritual practices, achieving Padmasana requires open hips and a flexible body. It signifies not just physical flexibility but also mental discipline.

3. **Urdhva Dhanurasana (Wheel Pose)**: This backbend is both exhilarating and challenging. It requires strength and flexibility in the back, shoulders, and arms. It’s often seen as a symbol of openness and fearlessness.

4. **Natarajasana (Lord of the Dance Pose)**: This balancing pose requires strength, flexibility, and focus. It’s a beautiful expression of grace and poise, representing the balance between effort and surrender.

5. **Paschimottanasana (Seated Forward Bend)**: This forward fold is deeply introspective and requires patience and surrender. After years of practice, it can become a signature pose representing inner peace and introspection.

Ultimately, your signature asana should be one that resonates deeply with you, reflects your journey and intentions in yoga, and brings you a sense of fulfillment and accomplishment. It may not necessarily be the most advanced pose, but rather one that holds personal significance and embodies the essence of your practice.