Moderate plus or a high profile. I am for sure getting 500cc, but I'm not sure which would look best on me? (Photo)

HP implants, which are a more modern shape than moderate
profile implants, fit most women better. They have a more appropriate
base diameter and can be made to look very natural or very augmented, depending
on where in the range the implants are filled to achieve a particular volume.
High profile implants are the first choice in my opinion. I rarely
find an indication to use moderate or moderate plus implants. The
subtlety in the final outcome is not achieved by which profile implant is used,
it is determined by the skill in the creation of the pocket, the choice of
volume, and where in the range the implant is filled.

Thank you for the question and pictures. Based on your photographs, I think that you are starting at a good place and should have a very nice outcome with breast augmentation surgery.  Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery (regarding breast implant type/size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. In bra sizers can be useful communication tools also. I have found that the use of words such as “natural” or "C or D cup" etc means different things to different people and therefore prove unhelpful.
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate. The use of computer imaging may be very helpful during the communication process.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery ( after the use of temporary intraoperative sizers).
I hope this, and the attached link (dedicated to breast augmentation surgery concerns), helps. Best wishes for an outcome that you will be very pleased with.