Crown or veneers ?

If you were my patient, I would recommend a crown.  The crown removes more tooth structure, but provides a more permanent and more cosmetic appearance.  A strong emax crown or a zirconia may be the best choice, cosmetically.  The costs should be relatively the same ranging from $1,000-$2,000 per tooth, depending on where you live.  I hope everything works out for you and good luck.

If a front tooth that had root canal more than 20 years ago is beginning to break down and micro-cracks or fracture lines are evident, I would recommend a crown instead of a porcelain veneer. Though a veneer might be a more conservative approach, 20 years of wear, tear and breakdown on a non-vital tooth is best served by having a full coverage crown restoration. Please keep us informed of your decision and the treatment performed.

If your discolored front tooth has much good tooth structure remaining it is almost always better to do a porcelain veneer than a crown.  The tooth underneath the veneer will be much stronger than a tooth that has had a crown, as full crowns require much more drilling down (preparing) of the tooth than teeth that have had veneers.  If your dentist uses a strong porcelain like EMax for your veneers, it will also strengthen your teeth considerably. 

Generally we strive to save as much tooth structure as possible. However, after a tooth has been root canaled for several years it begins to darken and become increasingly brittle. This makes it succeptable to fracture. For a tooth that you have described i would most likely recommend a crown due to the increased protection gained by covering the entire tooth which will help to prevent tooth fracture. Good luck and best wishes.