The P90 sprays too fast and that is why everyone uses it. You can run around the corner and spray with it and still kill the guy. I'd rather use the MP5 for anything, even if it is for a silenced weapon.
go with the p90 and throw on some steady aim...yeah definitely a noob technique but who cares, when i run around the corner and blast you without having to pull up a scope or ironsights you die and im alive