If you are looking for style points, 245.45's will look good. They will visually fill the wheel well better than 245/40's.
They are taller than stock so they won't do your acceleration any good (unless you are currently traction limited or make more torque than you can use at 2400 RPM - like a turbo buick)
You may need to take a heat gun to the back side of the inner fenders as a taller tire may rub when turning. In back there should be zero issues with 245/45's..
As I said, If it was me, I would go 255/40's and perform the inner fender lip surgery needed to get them to fit, but that is me. Everybody is different.