Samsung Exynos 7420 Advantages
Larger memory bandwidth (24.8GB/s vs 14.9GB/s)
Higher Frequency (2100MHz vs 2000MHz)
Lower TDP (7W vs 9W)
Qualcomm Snapdragon 670 Advantages
Better graphics card performance FLOPS (0.3584 TFLOPS vs 0.1976 TFLOPS )
More modern manufacturing process (10nm vs 14nm)
Released 3 years and 4 months late