I didn't like the way eight of these mercury fillings looked in my molars...not to mention the headaches etc. they were giving me. (a long story)
I just decided to change them out for cosmetic purposes, even though there are different opinions on their safety. I got porcelain and an excellent dentist that put them in over 10 years ago. It might have been over 12 years ago...kind of lost track of time.
Porcelain is much better than composites in my opinion, and there are so many different kinds of porcelain fillings that are reportedly better and stronger than others. You'll need to find a dentist that has done lots of these kinds of dental restorations...and find the materials that will be most durable and right for you.
I've had good luck with mine, with absolutely no problems...love my white teeth.