This study focuses on Wire Arc Additive Manufacturing (WAAM) of 5356 aluminium alloy. An approach combining designs of experiments and artificial neural networks was implemented to identify the optimal parameters for three MIG welding synergies: pulsed MIG, mixed CMT and pulsed MIG, and CMT MIG. The selected optimisation criteria were material health and the visual quality of the samples. The results obtained showed good material integrity for the three configurations studied (in all cases, the porosity rate is below 0.2%). The optimised samples were then subjected to mechanical and microstructural characterisation. The hardness measurements revealed a good level of homogeneity across the wall section and between the different configurations, both in the as-manufactured state and after annealing treatment (1.5 hours at 350 °C). The as built mechanical properties are consistent with the hardness values, with a tensile strength ranging between 250 MPa and 270  MPa. Slight anisotropy is observed between the building direction and the longitudinal direction of the test specimens (a difference of 2% to 4% in Rm and Rp0.2). The microstructural analysis of the three configurations revealed similar structures, characterised by columnar grains in the core structure of the beads and fine-grained interfacial zones, contrasting with the structures resulting from conventional welding. This difference is a consequence of an increased concentration of constituents, dispersoids and precipitates in the fine-grained zones, promoting abundant nucleation and selective grain growth. The phases were identified by Energy Dispersive Spectroscopy (EDS). Lastly, a correlation between the microstructure and the mechanical properties was established, highlighting a good match between both aspects.