Okay, I can give you a ridiculously overgeneralized answer, or I can tell you the truth: It doesn't matter. You can make a 4-1 that acts like a 4-2-1 (Short primaries), and you can make a 4-2-1 act like a 4-1 (long primaries before first merge).
Now, on to overgeneralization. 4-1 makes more top end power, 4-2-1 makes more midrange power, and Chevy makes low end power.