Following factors are taken into account while choosing an anchor position -
1. Distance off from other vessels
2. Distance off from nearest danger
3. Nature of holding ground
4. Own vessel size
5. Duration of stay at Anchorage
6. Weather forecast
7. In Case own vessel has to undergo repairs at anchorage ( immobilisation)
8. Presence of underwater obstructions
9. Any other factor which affects the safety of vessel directly or indirectly