For your D5500, all three can work, but they have different strengths.

For astrophotography, the Rokinon 16mm f/2.0 has an advantage because it’s about one stop faster than an f/2.8 lens, which helps gather more light. The Rokinon 10mm f/2.8 is wider, but ultra-wide lenses tend to show more distortion, which can affect both landscapes and night-sky compositions.

For landscapes, wider isn’t automatically better. Ultra-wide can be great for dramatic foreground-heavy scenes, but 10mm can look exaggerated and distorted if that’s not the look you want.

The Tokina 11-16mm f/2.8 is a strong all-around option because it gives you zoom flexibility, a useful ultra-wide range, and support for filters. If you want one lens that can cover both landscape and astro reasonably well, it’s probably the most versatile choice of the three.

So: choose the 16mm if low-light astro performance is your top priority, the 10mm if you specifically want an ultra-wide look, and the Tokina if you want the best balance of flexibility and usability.