Those are all models of different ages. The G5 came out in 2019, G6 in 2021, and GT in 2022. EVGA also doesn't make their own PSUs so each model has a different OEM. G5 OEM is FSB, G6 is SeaSonic, and GT is HEC. Of those the G6 and GT are the overall best, however, in 2025 it doesn't make sense...