I do not have any experience with lava crowns but I do other all porcelain crowns which are very similar. I am more inclined to do anterior crowns in all porcelain. The technology today produces very esthetic restoration.If the restorations do not match to your satisfaction then I think this has to be discussed with your dentist. Preop study models are often very helpful.
In an ideal situation, a diagnostic wax up should have been made of what you want your teeth to look like (size wise) for you and your dentist to approve before the crowns were made and if the lab is local you should have been sent there for their techncians to do a custom shading. The dentist should have also taken a mold of your teeth BEFORE he startied working on the teeth so the lab could get a good idea of the size of your original teeth for reference. hopefully that was done.
I would discuss these issues with your dentist and make a deision together on which is the best for you.