This work presents a finite element analysis of PneuNet-based soft actuators with different internal chamber geometries, aimed at identifying geometry-dependent trade-offs relevant for variable-stiffness actuator (VSA) applications in wearable exoskeletons. Using a Yeoh hyperelastic material model with explicit inter-chamber contact, quasi-static pressurization is simulated to evaluate bending angle, base reaction torque, stress and strain fields, total strain energy, and contact behavior. The results show that chamber geometry critically governs pressure-to-bending efficiency, load-bearing capability, and deformation energy accumulation. In particular, the rounded-rectangular geometry (P-RR) achieves the largest bending angles and highest strain energy, favoring motion amplification and stiffness modulation potential when coupled with a jamming interface. Stress and contact analyses further emphasize the role of geometric smoothing and wall orientation in controlling stress localization and inter-chamber interaction, which are key factors for durability and effective stiffness modulation. Overall, the results provide geometry-level design guidelines for selecting the soft backbone of jamming-based variable-stiffness actuators under application-specific requirements.