Maps and lists solve different problems. A list stores elements in a numbered sequence. A map stores elements by a custom key. Here is when to pick each one.
Use a list when your data is ordered by position and you access elements by index. Scores for a sequence of rounds, characters in a string, or tasks in a queue are all list problems.
Use a map when you look up values by a meaningful identifier. A user's name to their score, a product ID to its price, or a character to its frequency are all map problems.
If you catch yourself scanning a list to find an element by some property, that is a sign you need a map. A map gives you time lookups where a list costs time. Both use space for elements.