I had root canal on my left front tooth, the one next to it, and a filling on my right tooth. What's my best option? (Photo)

Your photo shows that you have very short "chicklet" like teeth.  These are often bad candidates for a natural looking smile.I would suggest the first step is to esthetically reshape the gingiva to give a more pleasing smile line and shape to your teeth.When you have had a root canal on the front tooth it may be best to have a crown on that tooth depending on tooth structure remaining and a post and core reinforcement.   If the two central incisors have the same treatment it is easier to get the best esthetics   Veneers are probably the best choice for the lateral incisors.There is considerable anterior wear and so nighttime bruxism guard is probably indicated.Natural looking smiles are like art work, all the components must blend.  It is important to look at smile lines and lip positionWhite is not natural,  a color that matches the other teeth is important so if you want to go lighter bleach the other teeth first.  the anteriors can be brighter slightly than caninesA fell perfect smile would probably include growing the posterior maxilla wider to eliminate the "dark Tunnels" between your teeth and cheeks"  A DNA appliance could easily accomplish this over time .  Zirconia is not as pretty as e-may or empress but it is stronger.  Empress or empress esthetic give gorgeous results.  You may want to consider stronger material if you try to restore natural tooth length.

 Veneers vs Crowns vs Dental tooth bondingDental bonding is the least invasive dental treatment, and that is great thing !   The draw back is the staining on the long run, due to the porosity of the composite bonding and the strength of composite bonding, meaning it is not a strong material at the chewing edge of your teeth, it can fracture ! The best thing about bonding is that very little or in some cases no preparation for the teeth is required (very little or no tooth removal is required), hence it is conservative dentistry, and there are many indications to use tooth bonding material, which is dependent on the forces of the patient bite.Dental crowns, are very strong, will last you a long time,and again has it's indications,where the tooth needs total support to function, due to severe caries, trauma, fractures, cracked tooth, teeth with root canals and proper walls remaining and many more instances in which is beyond the scope of this article.The drawback to dental crowns:A 360 degrees tooth preparation is required, meaning the full circumference of your tooth, and once your tooth is cut, there is no way to add on the original tooth structure back. In the past, for any cosmetic dentistry rejuvenation of the smile line, before the advent of porcelain veneers technique, most Holly Wood icons and celebrities did their cosmetic dentistry with Hollywood cosmetic crowns, since Dentistry had not introduced veneers procedure and technique, in which can even produce better results. Again there is indications to use crowns or caps, if strength and protection of the tooth is needed due to bite and occlusion, then a full coverage crown is needed for your teeth to function properly, then crowns will be the material of choice.Dental Porcelain Veneers, are between dental bonding and crown procedure , they are much stronger than dental bonding, they are NOT porous, and they are much more conservative than crown procedure, and minimal tooth structure is required to remove, and that is the beauty, and if done properly and conservatively by your dentist, it will last years more than dental crowns.The most important thing to consider, they are less invasive than crowns.Also you must know that if for some reason in the future, the porcelain veneer fails, you can always have a crown made, however if the crown fails, you can not have a porcelain veneer done.In Your case, since you do want to have cosmetic dentistry done, first thing is to check your gum architecture, if you do have uneven gums they need to be addressed first, since if not treated your teeth might look, longer or shorter to the eye, although the edges of your teeth looks even.The next step is to check for any discoloration:The discoloration due to root canal, or other intrinsic discoloration must be addressed first, either through internal bleaching procedure such as "Walking Bleach" procedure, to correct the color prior to having further cosmetic dentistry done such as veneers or porcelain crowns. Please be aware if you do not correct the color of your tooth prior to veneering or crowning, the color might show through again, several years later.Once the color is corrected then consider if you do want to enhance the shape of your teeth, via veneers, or crowns. Since your teeth are healthy, and you want to have a brighter and more attractive smile, I do recommend veneers, since it is conservative, and will give you an awesome look vs crown, in which a lot less of your precious tooth structure needs to be cut away with the veneering technique. You may ask your dentist to show you a waxup of your teeth, and also show you on your study model, the preparations of your teeth and even the outcome you desire prior to starting the procedure, there is cost involved, but it is worth it.Hope above helped you in your decision making.