If you've already had your teeth prepared (drilled to proper shape) for porcelain veneers, then you would be best off completing the porcelain veneer process. In general, porcelain veneers look much better than composite bonding. The three advantages of composite bonding is that less tooth needs to be prepared (drilled on), can oftentimes be done in only one visit, and lower cost than porcelain veneers that require a lab fee for the ceramist to make the porcelain veneers.
If you didn't like the veneers that your dentist tried onto your teeth, then your did the right thing by not accepting them at the try in stage. It is much better to put back the temporary veneers and have the lab redo them than to bond them into place and then later have to drill them off to redo them.
Communicate accurately about what you don't like about the way the porcelain veneers were done so that the ceramist can make the appropriate adjustments. Ask your dentist if he/she used a dedicated cosmetic dentistry lab, or an ordinary dental lab that does most everything. Believe it or not, some labs do better cosmetic work than others. Things to discuss with your dentist are the length, shape, color, surface texture, incisal translucency and balance and proportion of all the veneers.