Performance is sufficiently close to make it a preference call in my opinion. MP7 is usually placed immediately above the Vector in SMG tier lists, but some may prefer the Vector's irons or almost total lack of recoil.
Vector is better. Range difference is insignificant, but the difference in recoil pattern is huge.
What good is a gun that can't stay on target? MP7 recoil bounces horizontally and cannot be consistently controlled like the upward recoil of an MSMC/Skorp. And well the Vector recoil doesn't even exist so there is nothing to control.