This study extends the Equal Criteria Influence Approach (ECIA) by developing its subjective counterpart, the Subjective Equal Criteria Influence Approach (SECIA), to enhance its applicability across a wider range of decision-making problems. The proposed method is evaluated using a case study focused on assessing healthcare sectors in Eastern Europe, with the Stable Preference Ordering Towards Ideal Solution (SPOTIS) method employed to construct the decision model. SECIA’s performance is compared with two widely used weighting methods: the Best-Worst Method (BWM) and the Level-Based Weight Assessment (LBWA). Additionally, a simulation study incorporating correlation coefficients and similarity metrics provides a detailed analysis of the differences in criteria weights and rankings derived from these methods. The results demonstrate SECIA’s stability, flexibility, and alignment with established methods while highlighting its unique ability to directly adjust the influence of individual criteria on ranking outcomes. These findings underscore SECIA’s value as a robust addition to the MCDM toolkit, particularly in scenarios requiring subjective input from decision-makers. Possible avenues for future research include extending SECIA’s application to diverse decision-making contexts, formalizing its mathematical structure, and further exploring alternative approaches for determining the impact of criteria.