Hello - I think the answer to your question depends on how you feel about your current breasts, specifically the position of your nipples. If you don't mind them being a little bit low, then a modest augmentation will give a bit more volume and fill out the upper part of the breast. And you will avoid the cost and scars associated with a mastopexy or lift. It is important to understand that because the breast is somewhat low, the implant will need to be placed low, which will limit the surgeon's ability to place the implant under the muscle (which is higher on your chest than the breast). Because the augmentation will be only partially under the muscle, or perhaps not at all, you will be at increased risk for capsular contracture. Using a textured implant can reduce this risk, but there is an extremely rare form of cancer (ALCL, or anaplastic large cell lymphoma) associated with textured implants as well. This cancer is usually curable, and it is extremely rare, but it's been in the media so I feel compelled to mention it. Some surgeons will place large sub glandular implants (over the muscle) in patients like you, which will fill out the excess skin and provide somewhat of a lift. I strongly advise against this misguided approach, as it further stretches the skin and compounds the underlying problem. In this situation, when you eventually develop issues related to the implants (want them removed, downsized, a lift, etc), it becomes a very difficult situation requiring much more involved surgery with increased risk of complications and less guarantee of an optimal result. The skin and breast tissue is stretched out and thin, and when the implant and capsule are removed, performing mastopexy can be risky due to poor blood flow to the skin. For this reason, we often do the implant removal and mastopexy in two stages (3 months apart). You don't want to go there - trust me!
With regard to what type of implant to use, I think a textured round silicone or saline implant is best to reduce the risk of capsular contracture in the sub glandular plane, but there are a lot of opinions on this matter and it's best to discuss things with a board certified plastic surgeon. Some surgeons believe the anatomic or "tear-drop" shaped implants provide a little lift to the breast, but several recent review articles have shown that in most cases there is no difference, so I would recommend sticking with round implants. In your case, if you go with a smaller implant, then the overlying breast tissue will cover the implant nicely and you won't be able to tell the difference between a silicone vs saline or round vs shaped implant. I actually recommend saline implants in patients like you because in 5 or 10 years if you are thinking of having them removed but unsure whether you want to replace them, have a mastopexy, or both, then it is easy to rupture the implants in clinic with a needle, draw off the saline, let your body absorb the rest, and then watch over several months as the breast contracts and you can see where you are at ground zero and make a much more informed decision as to how to proceed.
In short, I think you would be happy with small implants (250-350) but you can't expect a miracle, and you will likely require some type of mastopexy in the future if you want the nipples to be higher. With time, the breast tissue and nipples will continue to sag over the breast implants resulting in the "Snoopy" deformity... Best of luck!