The Corsair AX1600i wins in 4 out of 9 comparable specs, with 4 ties. Its biggest advantage is PCIe Connectors (150% better).
Focus GX-750 wins in 1 spec (MSRP: 83% better).
Recommendation
Choose AX1600i if you want the best overall performance — especially pcie connectors.
Choose Focus GX-750 if msrp matters more to you.