480 is okay for GBA but not for GG / GB / GBC. You can't integer scale without losing a lot of space.
406V/H is 720 vertically which is an integer multiple of 144 for GG / GB / GBC. And 960 horizontally is an integer multiple of 240 for GBA, with minimal loss vertically (very small black bars). And as it is a 4/3 screen, you are filling a ton of space, so it just feels right. For GG this is a perfect fit actually, you fill the entire screen while being integer scaled both vertically and horizontally, and with the 4/3 ratio the original screen used.
In summary, I would pick 406V/H any day rather than what you talk about.