What dermal fillers or procedure(s) would make the biggest difference in facial harmony?

I think it's really up to you to explain to us what it is that you don't like about your face as there really isn't anything that's out of ordinary, because everyone has a different face since their genetic makeup is completely different. The only thing that I could recommend, would be to create less of a pointy  chin and more of a square jawline that is still feminine. This can be done with either your own fat which will give you a natural and permanent result or a number of fillers that are available on the market today. Most fillers will give you the same results lasting anywhere from 6 to 12 months but make sure you go to a plastic surgeon who understands your needs and requirements, and has a good reputation. I hope this helps and good luck from New York City plastic surgery

Hello, thanks for sharing your pictures with us. Definitely one of the most used treatments all around the world are dermal fillers, in the right hands, placing in the right layer and the right product, you can have amazing results in order to look rejuvenated. Don't forget to go with an expert aesthetic physician to set a plan according to your needs and follow up too. 
Dr Luis Salazar
Aesthetic Solutions

It is important when considering fillers that you address the things that bother you versus what another's opinion may be.  You can work together with your injector to select the products and treatments to best help you achieve your desired look.  We always recommend using medical grade skin care and wearing sunscreen every day.

I think you look quite good. At 30 years you are starting out on a journey of maintaining your looks, and my advice is to do two things, prevent ageing with the help of Microneedling and Botiox and restore volume loss with dermal fillers. from the photos you have submitted I would suggest that the biggest bang for the buck would be undereye dermal fillershope it goes well for you, do get in touch if you need further advice, best wishes Dr Prashant Murugkar

Based on the photos, I think you would benefit most from filler injections to the lower face. I would recommend treating the lateral chin, prejowl, and marionettes lines using an HA filler like Restylane Lyft or Restylane Defyne. I would also add a little filler to the upper lip and possibly the cheeks. The best thing for you to do is schedule an initial cosmetic evaluation with an experienced aesthetic physician in your area.