In no world was the Game Gear a mark of the Golden Era of Portables.
I assume you're joking, but taking it serious, but there was not much great about this era of portables aside from that they pushed each other to innovate a little bit with competition. I loved my Atari Lynx (and like 4-6 games on it,) but neither Lynx or GG were must-own platforms for hardcore gamers, and their battery life and weight made them tough to actually take with you. Game Boy thrived because Nintendo had the touch, but even that wouldn't be considered by most to be the golden era of Nintendo portable games.