I have been researching the same. I was using the agglomerate corks most used but I hear so much conflicting information about their half life (how long they last) and started trying other types. I have bottled my last few batches of wines I think I might have on hand for a while (big reds) with Altec corks (a combo of real cork and synthetic) which are what many wineries use and supposedly have an up to 10 year life span. My next 2-3 batches will be bottled using Neocorc full synthetics. When you read up on various corks you will always hear good and bad stories so I guess I just have to try them myself.