Schools' priorities in student selection constitute the basis for fairness in school admissions. We study the case where schools are active strategic players that rank their applicants in terms of priorities. A methodological framework is developed to examine the impact of the variation in the admission settings on the equality of opportunity in access to high-quality schools. The school's priorities are formulated following a Multi-Attribute Decision Analysis (MADA) approach with several scenarios including geographic, family, academic, and socioeconomic variables. The matching is simulated using student preferences, multiple assignment algorithms, varying school capacities, and changing priority profiles. The Human Opportunity Index (HOI) logistic regression approach is used to examine how far from, or how close the admission is to being an equitable assignment, i.e., one that gives equal opportunities to children with different backgrounds. The analysis is based on choice admission data from a large specialized (magnet) middle school program in Florida. The results suggest that how the school priority is designed slightly affects the equality of opportunity. The second impact is due to the algorithm used to perform the selection. The availability of places in high-quality schools has a big impact and is tightly correlated with the parents' satisfaction with their most preferred school choices.