I did a request for "lots of good animal viewing". My room was near the end of Kudu trail on the 3rd floor overlooking Arusha. I like the 3rd floor a lot because it's on the same floor as the lobby. The animal viewing was great as the animals were being fed nearby. I felt like we got good close-up views of the animals and a good panorama of the Savannah.
However the pool and Mara, the quick service, are on the Zebra Trail side. I didn't mind since I didn't use either. But if the pool or access to the quick service is important to you, you'll probably want to request Zebra trail. I was offered the first section of Zebra trail but I turned it down because I thought there would be lots of traffic by my door from people going to the elevator for other floors, the pool and Mara.
After looking at the map, it was a coin flip for me for either Kudu or Zebra trail 3rd floor. But I knew I wanted to be past the first bank of elevators on either side to minimize traffic by my door. I wanted the 3rd floor because it felt closer to the lobby since I didn't have to use the elevator or stairs. However there are porch areas on the second floor with rocking chairs, which is also very nice.
The morning sun came directly into my room at the end of Kudu trail, so I'd guess that the end of Zebra trail has a western view. Western views can be quite hot in the summer.
However all of this is a bit of splitting hairs. As I think I would've enjoyed any of the Arusha Savannah rooms. It's a gorgeous resort!