Silicone breast implants vs. saline: how does one choose the best type of implant?

In general, gel breast implants look and feel more natural.  Saline implants are less expensive, and may be somewhat more helpful if there is a significant breast asymmetry that needs to be corrected, because the saline implants can be filled on the OR table within a range of volumes.  There are also different types of implant shapes and projections, as well as different access incisions, including completely away from the breast itself (transaxillary), and different planes of placement within the breast, so it is best to review these details with your surgeon during your consultation.

Ultimately, the answer is...they are different not better or worse but different.Saline vs. Silicone differences include:
-The "feel"- silicone is more natural
-The "look"- silicone is less prone to rippling
-The "cost"- silicone is more expensive
-Access incisions- saline can be placed through a smaller incision as they are empty at the time of placement
-Customization-Silicone implants are pre-filled to a particular volume. Saline can be adjusted on the table within a recommended range.
-Monitoring-Saline implants, if ruptured, will deflate and the saline fill will be absorbed. Silicone implants require surveillance MRI's at 3 years and every 2 years after.
Patients prefer silicone devices for the more natural feel and the decreased incidence of rippling. In my practice most patients will choose a smooth round device over a textured shaped device ("gummy bear"). When placed in the submuscular plane, the aesthetic differences are minimal. The downward pressure by the muscle across the upper pole of the round device forces it to assume a more tear drop appearance. Recent studies have shown that both patients and surgeons have difficulty distinguishing between the 2 implant types post-operatively. Additionally, shaped implants are more costly and have a risk of malrotation.
Finally, although very rare, the few documented cases of BIA-ALCL (Breast Implant Associated Anaplastic Large Cell Lymphoma) have all been in cases of textured devices (shaped form stable or "gummy bear"). Until more data is available many are shifting their practice back to smooth round devices.
With regards to your specific question, choosing is personal. That being said, most patient select silicone for many of the reasons listed above. The Ideal Implant (a new entry to the field- a saline filled implant with internal baffles/supports to give a more silicone like feel) may be another option to consider although this is only available to a few select providers (early adopters/investors).
Your board certified plastic surgeon (ABPS) should be able to help you select an implant type/size that satisfies your goals.

There are quite a few choices when it comes to implant selection asides from selecting the different profiles. Silicone: there are 3 types of different cohesive gels that can be chosen.  There is "responsive, soft touch, cohesive".  The difference between the three is the degree of cross linking there is between the silicone gel molecules.  The responsive gel is  gummy gel, soft touch is gummier and the cohesive is gummiest.  The differences will show with the more cohesive the implant the less rippling, but the more firm the implant will be.  Silicone implants give the most natural feel to the breast when comparing them to saline implants.Saline:  there is the traditional, single lumen implant and now the IDEAL breast implant which is a multi lumen implant with baffles to help decrease the "sloshing" of the saline and give the implant a better feel.  Saline implants can give a natural look as well, however to achieve a natural look, the bag has to be filled less with fluid and now the chances of rippling are greater.  Fill the bag up and decrease the rippling but now you have a harder implant.From a safety standpoint: no difference between the two.  In fact a saline implant has a silicone shell as well.Adjustability:  the one advantage that saline implants have over silicone is the ease of adjustability while in the operating room.  Silicone implants come pre-filled therefore the increments of sizes may at times fall somewhere in between the asymmetry you are trying to fix.  However, with the newer Inspira line of implants, there are more options with sizes when it comes to silicone.Incision Size:  Not much of a difference here if the surgeon uses the Keller Funnel.  With the Keller Funnel a smaller incision can be made when placing silicone implants.Hope that clears things up a bit.