For me, there's no preference. I like all angles, high up on a footbridge, low down at ground level, watching from the safety of a platform. If you can include all those angles both inside and outside of the railway, you have a winner of perspective. This sort of decision is yours to make, you're the controller/videographer here. Next time you visit a preserved railway, walk up to the top of one of the footbridges. You will get the best panoramic views you'll ever feast your eyes on. It's one place where there are smaller crowds, usually.