Would it look more natural to have a wider implant with less projection than a narrower one with more projection? (Photos)

Hello there 
Both of those implants are of an appropriate volume . Width selection would be based on  a number of your tissue dimensions , including soft tissue pinch .
Your breast looks narrow so I would lean towards the narrower implant , unless you are trying to widen your breast base . Hard to advise without seeing you .
A Vectra 3D imaging session may help you decide .

Cheers
TS

It would be best to consult with a board certified plastic surgeon who has 3-d imaging software in their office that can simulate how different implants would sit in the body. Best of luck!

Profile terminology will vary from one manufacturer to the next. The terminology matters less than the correlate dimensional measures.
As one goes up in profile the footprint or BWD of the device will shrink and the projection will increase for a given volume. I have found that full profile Allergan implants correlate closely with high profile Mentor implants. These devices exhibit higher projection than similarly sized moderate (+)/moderate profile devices. Ultra high profile is simply the next step upwards in projection.
Patients are encouraged to stay within the boundaries defined by their BWD. This is the best way to avoid the dreaded "fake" look. I generally recommend that patients with smaller frames who are seeking more than a modest augmentation consider a higher profile device.The higher profile device will impart greater projection and thus a less subtle result but will allow for a more significant augmentation than a similarly sized Mod/Mod+. Thus, the ultimate question is one of volume. Is the volume you can achieve via a similarly sized Mod + profile implant adequate to reach your desired goals? If not, a HP will afford you more volume at the cost of subtlety.
The difference between higher and lower profiles for a given volume is projection and for a given width is volume (with the high profile implant being greater in both scenarios). The moderate plus is the most commonly used profile in my practice. It allows for the most reasonable volume in given BWD. In my practice, low profile implants are the least commonly used (widest and flattest). I will typically reserve high profile devices for smaller framed individuals or those seeking a less subtle more dramatic change (the opposite of natural). 
Smaller framed patients tend to prefer HP implants as their BWD can be restrictive with regards to volume. An HP implant will provide greater volume in the same BWD footprint. But remember "natural" while difficult to define often implies a good match between frame, volume and projection. If the goal is natural more conservative sizing/volumes are recommended.Based upon your photos, you have 2 options...a smaller volume and more moderate profile for a more subtle result or, alternatively, a higher profile device in order to achieve greater volume than is possible in a wider device at the cost of subtlety. The most important point is to stay within your unique BWD.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).

Hi there and thanks for posting,There is really a minimal difference between the two implant sizes your are choosing from.Both would give you an excellent result based on your dimensions.Probably of more importance is which pocket the implant is being placed in. In your case I would definitely advocate for a dual plane, as you dont seem to have much in the way of soft tissue in your upper pole.CheersRichard

It all depends on your definition of natural.  If your definition is that of a normal breast with a gradual slope, then a wider/less projecting implant is more "natural."  There will be a smoother transition between your chest.  If you like the upper part of the breast to be full and round, then a higher profile/narrower implant is the better choice.  That being said, I would not choose an implant that is wider than your breast width.  For that reason I would go with the 11.75cm wide implant 320cc.  Best of luck!