Among the three options you've mentioned, the best bike for touring with a good cruising speed of 130+ would be the Interceptor 650. Here's why:
Engine Power: The Interceptor 650 is equipped with a powerful 648cc parallel-twin engine that produces 47 horsepower and 52 Nm of torque. This provides ample power for highway cruising and overtaking at high speeds.
Torque Delivery: The Interceptor 650's engine delivers strong torque in the low and mid-range, allowing for effortless acceleration and smooth power delivery. This is beneficial for touring as it provides good response and flexibility in various riding conditions.
Stability and Comfort: The Interceptor 650 features a stable chassis and a comfortable riding position, which is ideal for long-distance touring. Its relaxed ergonomics and upright seating position reduce rider fatigue during extended rides.
Reliability: Royal Enfield bikes, including the Interceptor 650, are known for their durability and reliability. This is crucial for touring, as you want a bike that can handle long distances without frequent mechanical issues.
While the Ninja 300 and Duke 390 are both capable bikes, they may not offer the same level of comfort and stability as the Interceptor 650 when it comes to long-distance touring. Additionally, the Interceptor's larger engine displacement provides more power for sustained high-speed cruising.
It's important to note that personal preferences can vary, so it's always recommended to test ride the bikes you're considering and choose the one that feels the most comfortable and suits your specific touring needs.