The period from December-February in Year 1 was the most balanced IMO. Every primary except for pulse rifles were viable, shotguns, fusions and snipers all balanced, it was just reliant on skill mainly. The only missing piece was pulse rifles needing a buff, but instead, they nerfed autos into the toilet, exotic hand cannons became the king, and Felwinter's tier shotguns were introduced, then it was all downhill from there.