Things that are net positive:
- Proximity to family
- SO located in city
- SO willing to relocate but their career only has jobs available in certain cities
- Ability to tolerate being in said city (having lived here before, went to undergrad here, been in similar towns/cities, etc.)
- School- or city-specific things, e.g someone who is interested in infectious diseases or epidemiology may want to be close to the CDC for fellowship opportunities, etc. (a weak positive)
- Essentially, any reason that would make an applicant choose us over a similarly-ranked or higher-ranked school
Things that are net negative:
- Not showing enough interest to even look through the school website
- Wrong school name in the application... Most "top" schools probably get very touchy when they're accidentally called Harvard
- No clear reason given for why you would even consider coming here if accepted (probably a bigger issue for lower-ranked schools, or for schools located in the middle of nowhere)
These lists are obviously by no means exhaustive. For the overwhelming majority of folks, they'll be putting down more or less the same things...
Just don't write something that would make you stand out negatively and you'll be fine. Not worth delaying a secondary for this.