What is the most long term fix for nasolabial folds?

Congratulations on taking care of yourself and looking young for your age! It would help if you would post photos so that we could answer you more specifically. In general, I would not recommend fillers except to counter the very early stages of aging – usually in the 30s and 40s. Once there are significant creases and sagging, the best “fix” is a Mini Lift. In my practice a Mini Lift addresses lower face sagging and smooths out the jawline.  It can include a neck lift with platysmaplasty to clean up the neckline if indicated. It's a very rejuvenating procedure that will turn back the clock about 8 years and last at least that long, too.
I don't have personal experience with Sono Bello, but have not been impressed with the long-term results of nonsurgical skin-tightening procedures; they don't last. Liquid face lifts also must be repeated every year or two. The costs of these procedures add up quickly. If affordability is your main concern, you may be able to work out a payment plan with your facial plastic surgeon. I hope this helps.

I recommend fillers to soften the nasolabial folds themselves and also lift around the mouth and cheeks to build underlying anatomical support. In our practice we combine Sculptra with other fillers "layered" on top and lasers, skin tightening treatments such as Thermage, Fractora, and Renuvion (J Plasma), thread lifting, and peels to get the most conservative, natural look. I suggest seeing a facial sculpting expert for a formal consultation. Best, Dr. Emer

Thank you for your question, unfortunately if there is skin laxity where it has lost elasticity only surgery would address this.  Putting fillers in the nasolabial folds would just create more heaviness, making that area look more prominent.  
Most of my patient want to remove the skin laxity however do not want the downtime associated with a traditional facelift.  The Concept Facelift is the procedure I perform, which combines the latest surgical techniques with the use of local anaesthetic to dramatically reduce the risks associated with traditional facelifts, while significantly reducing the bruising and downtime of your recovery, from months to a matter of days. 
If you have lax facial skin, lost volume and feel that you have jowls and wrinkles on your cheeks and you look tired when you're not then the concept facelift can help improve your appearance. With concept facelift you will look natural and fresh just like the way you feel inside. There are no bandages, drains and hospital stay but with lasting results of traditional facelift techniques it fits with today's age.
What are the benefits of a local anaesthetic facelift?
Minimally invasive as it is a short scar faceliftThere is minimal bruising and swelling, especially when compared to traditional faceliftsAs the procedure is performed under local anaesthetic, you can go straight home following the procedureFull recovery in a matter of days rather than monthsSignificantly less risk than Facelifts performed under general anaestheticFresh, youthful and long lasting resultsPlease make sure you find a reputable and qualified plastic surgeon who can assess you properly to give you a realistic idea of what outcome you can achieve.  All The Best