If it's convenient, try to keep the battery between 20% and 80% most of the time. This will ensure maximum longevity of any Lithium battery.
However, Lithium has come a very long way. Newer cells are far more tolerant to being charged to what the phone indicates as 100% or running the battery down to phone shutdown, and phones have become better at battery management. So any additional wear and tear on the battery will be pretty minimal.
Plus, one of the reasons I stubbornly cling to my Note 4 is the fact that I can swap batteries. That's some concentrated awesome right there.