This manuscript presents a comprehensive performance analysis of a proposed Kretschman configured Tantalum Disulfide (TaS2) mediated Symmetric Long Range Surface Plasmon Resonance (SLRSPR) biosensor. The sensor performance is optimized and compared for different metals (Au, Ag, and Al) and four dielectric buffer layers, DBLs (LiF, Teflon, Cytop and MgF2) to explore the best suited metal and DBL. The 27 nm thickness of Al and 1000 nm of LiF has demonstrated the best performance by achieving smaller full width at half maximum (FWHM = 0.03 Deg.), higher values of detection accuracy (DA = 33.33 1/Deg.), imaging figure of merit (IFOM = 431933.34 Deg.−1RIU−1), and imaging sensitivity (Simg. =12958 RIU− 1) for the proposed SLRSPR biosensor. The proposed LRSPR sensor show 45.32 times higher Simg., 181.03 times higher IFOM, and 4.37 times higher DA than conventional SPR (CSPR) sensor. Furthermore, it exhibits 6.76 times higher Simg., 13.52 times higher IFOM., and 2 times higher DA than the conventional LRSPR (CLRSPR) sensor. The proposed SLRSPR biosensor shows the highest PD (401.5 nm), indicating deep analyte sensing. The work presented here highlights the significant potential of the proposed SLRSPR biosensor in biomedical applications that require highly accurate and sensitive refractive index sensing.