I don't think I can give an accurate answer without knowing more, seeing a photo of the tooth in question and the radiograph (x-ray). However, there is a changing consensus in dentistry on whether or not to place a veneer or crown on a root canal tooth. The old thinking was to always place a crown on a root canal tooth. The newer thinking is to preserve as much of the tooth as possible, meaning place a veneer rather than a full crown restoration. One thing happens when the dentist prepares a tooth for a full crown, he removes the bump on the backside (tongue side) of the tooth, called a cingulum. Some studies have show that when this is drilled away for full crown preparation that the tooth becomes 50% weaker compared to a tooth that had a porcelain veneer and did not have the cingulum drilled off.
I have done many cases where one of the front tooth is a porcelain veneer and the other is a porcelain crown. However, you get the best match in color, shape and contour when both front teeth are prepared the same way (i.e. either for full crown or porcelain veneers).
So, saying all of this, but not having the opportunity to actually evaluate your teeth, all I can say is that if you consulted ten cosmetic dentists my bet is that you would get three different answers. Several would agree with your dentist and do one crown and one veneer. Several would want to do full crowns on both teeth. And the remaining, like me, would prefer, if possible, to do two porcelain veneers.
One last thought. Your dentist might recommend placing a post in the top 2/3 of the root canal tooth. This is a good idea, as it will strengthen the root canal tooth considerably. However, make sure he uses a bonded fiber post (it's like kevlar fiber, strong as metal, often used in bullet proof vests), and does not use a metal post. A metal post can't effectively be bonded into the root canal space and also may case a dark shadow that will make that tooth, and veneer or crown, look darker than the non-root canal tooth.