Yes, one or the other... I have a funny shape. Big neck (17"), but otherwise a 42 regular (suit). So either I wear shirts that are way too big, or buy Jantzen. Jantzen has been sort of a let down, including poor fit in places.
I just tried a TM Lewin (OTR), getting closer. Thomas Pink are like tents, Zegna is too baggy and the neck is too tight on the 43.
It's just not easy, and I certainly cannot afford bespoke at this stage in my career.