Is Index Used for This Query
The reason you can't tell which one is being used is because of a bug whereby explain does not include the index name of the index being used for geo index queries:

https://jira.mongodb.org/browse/SERVER-4213

What we do know is that it has to be one of the first two you have listed, that have a 2d element first.  It cannot be the "indexContents": NumberInt(1) index.  You can use .hint() to specify the index to use and then compare the results of the index in each case.  I would expect the first one to perform better in general (but be larger) since it contains all of the elements you are querying on:

"LongitudeLatitude": "2d",
 "Prominent"▼: NumberInt(-1),
 "indexContents": NumberInt(1)

However, that will depend on the actual data itself.  I would test over a representative set of queries and then remove the slower of the two indexes to avoid confusion.