Iterative Select by Location: Return the record with the most features in radius

I need to figure out how to determine which feature in a dataset has the most features within a defined radius.

I'm thinking I need to loop through the entire dataset, perform a Select Layer by Locaiton function, load the result ID and number of features into a list, and continue iterating only updating the list if another feature comes along with a higher number of features.

I'm open to ideas on how to best accomplish this.