I think the handheld era is my favorite, it basically ended with the 3DS, but it is the DS which I really can't put down, I am playing for the first time Chrono Trigger on it, and it is my Jump Ultimate Stars machine (Wimmfi), also have some other bangers as well, but I'll bore you if I citate them all.
But hey, don't get me wrong, the current handheld era is good too, we have the Switch, The Steam Deck and a plethora of good quality Chinese handhelds.