I would probably get a Corolla if my budget was 15. Might be tempted to look at a Cruze or Focus.
Not sure how big the driver is but you could also look at a used Optima. Around here a 2016 base model with about 12,000 miles is under 15. A Camry with about 20,000 miles on it should be in your budget. A Nissan Juke with similar miles would be an "interesting" option too.
Take a look. A lot of options.
Used Vehicles Under $15K | Duncansville, PA | Near Edensburg, & Huntingdon, PA