<p>This study investigates the mechanical properties of 3D-printed polylactic acid (PLA) components, analyzing the effects of raster angle, strain rate, and annealing on tensile behavior. A comparative evaluation of single-objective and multi-objective optimization techniques was conducted to determine optimal printing parameters for maximizing stiffness, strength, and ductility. Using Taguchi’s method and composite desirability function analysis (CDF), the study evaluated mechanical responses at three raster angles (0°, 45°, 90°) and three strain rates (10⁻⁴,10⁻³, 10⁻² s⁻¹) for both annealed and non-annealed conditions. The results indicate that multi-objective optimization is superior to single-objective methods, achieving a more balanced mechanical performance. The optimal configuration for non-annealed specimens—90° raster angle and 10⁻² s⁻¹ strain rate—achieved a composite desirability score of 0.71, with notable improvements in Young’s modulus (3820 MPa) and ultimate strength (55.9 MPa). Annealing further enhanced these properties, with a 12–15% increase in stiffness and a 5–10% improvement in strength, stabilizing mechanical responses across all configurations. The best annealed configuration—90° raster angle and 10⁻² s⁻¹ strain rate—achieved a composite desirability score of 0.92. ANOVA analysis confirmed the statistical significance of raster angle and strain rate, with strain rate having a dominant influence in the annealed state. These findings offer critical insights for optimizing 3D printing parameters and post-processing strategies, contributing to developing high-performance printed components for aerospace, automotive, and biomedical engineering applications.</p>