Please teach me about gearing and give me some advice

is a ratio a ratio, or does it make a difference for example

12 tooth front x 60 tooth rear is 5:1

13 tooth front x 65 tooth rear is 5:1 also

if those are the same why would you want to carry the extra weight of the larger sprockets and or require extra clearance and a heavier larger chain

right now I am running a 12 tooth front and a 46 tooth (OEM stock) rear for a ratio 3.8:1 call it 4:1

my top speed is barely 45 MPH, so I am torn with a decision, everything I read states that electric motors are happy at higher RPMs, so initially I was planning on replacing the rear sprocket with a 50 tooth one to give me that covetted 5:1 ratio, but then I am being told to go faster I need to lower the ratio and replace the front sprocket with a 13 tooth one while keeping the existing stock rear, which would give me a 3.5:1 ratio

are my goals of a higher speed and optimal motor performance mutually exclusive, or is there a happy medium?