To discuss the best choice of transport from Da Nang to Hanoi, let's evaluate the three options: by train, by plane, and by coach.

### 1. By Train
- **Pros**:
- Scenic views along the way.
- Comfortable seating options.
- Can be a social experience if traveling with a group.
- **Cons**:
- Longer travel time compared to a plane.
- May not be as flexible in terms of scheduling.

### 2. By Plane
- **Pros**:
- Fastest travel option.
- Convenient for long distances.
- **Cons**:
- Can be more expensive.
- Security checks and boarding time may add delays.
- Limited luggage allowance.

### 3. By Coach
- **Pros**:
- Typically the cheapest option.
- Direct routes may be available.
- More flexible in terms of schedule compared to trains.
- **Cons**:
- Longer travel time than both train and plane.
- Comfort levels can vary significantly.
- Restroom and food options may be limited.

### Conclusion
The best choice depends on the group's priorities. If speed is a key factor, flying is the best option. If cost and a more scenic experience are more important, taking the train might be preferable. For a budget-friendly choice with more flexibility, traveling by coach could be the way to go.

Consider factors like travel budget, time constraints, and the desired travel experience to make a decision.