1 being the first photo, 10 being the 2nd photo
Most Helpful Guy
Depends because there is such a variety of factors in play. The size, shape, complex. A good handful size on an average/slim 18-30 y. o. , about around 5-7 on your scale works great. Heavier weight, older, or other factors, would drop it under 4. But again, it all depends.
Most Helpful Girl
The second photo is definitely too much cleavage...
Maybe a 9 is too much...
Otherwise - with the right bra - it all comes together, man. =)
To be honest, it all depends on the kind of boobs you have...
Since she has really perky, firm ones, I'd say not even this is too much, it's just right:
This one is the farthest I'd go with these kinds of bigger breasts: