I went to Wikipedia because “I think” and “I prefer” are red flags in this conversation.
Warwick is a local government district in Warwickshire, England. It is named after the historic county town of Warwick, which is the district’s second largest town; the largest town is Royal Leamington Spa, where the council is based.
Warwick (/ˈwɒrɪk/ WORR-ik) is a market town, civil parish and the county town of Warwickshire in the Warwick District in England, adjacent to the River Avon.
Royal Leamington Spa , commonly known as Leamington Spa or simply Leamington [note 1](/ˈlɛmɪŋtən/ ⓘ), is a spa town and civil parish in Warwickshire, England.
Non-metropolitan districts, or colloquially “shire districts”, are a type of local government district in England. As created, they are sub-divisions of non-metropolitan counties (colloquially shire counties) in a two-tier arrangement. Non-metropolitan districts with borough status are known as boroughs, able to appoint a mayor and refer to itself as a borough council.
Typically a district will consist of a market town and its more rural hinterland. However districts are diverse with some being mostly urban such as Dartford, and others more polycentric such as Thurrock.
In England, a civil parish is a type of administrative parish used for local government. It is a territorial designation which is the lowest tier of local government.
A spa town is a resort town based on a mineral spa (a developed mineral spring). Patrons visit spas to “take the waters” for their purported health benefits.
I scrolled down to the US listing of spa towns, and can confirm these are viably used as cities in CityStrides.
All of this information is suggesting that admin level 10, when available and providing full coverage, is the most correct level to define a city/town.
I’m looking forward to feedback on this.