Batman 66 Refinery Edition
EDIT: Providing "why" as I just noticed OP requested this info as well as my post was down voted (I can only guess as to why as J85M is an enthusiastic BM66 owner himself).
Batman 66 has always had a nostalgic appeal to me as I enjoyed watching the original TV show as a kid. Although its gameplay was initially disappointing, it has now become very fun for me to play, and apparently is going to get even better with a lot more code upgrades yet to come. Consequently, it is the NIB game that appeals the most to me at this time - a decision I didn't make lightly as I gave up my shortly upcoming spot for a TNA in order to make this purchase.
Most of my Stern games are Premiums (where applicable) that I have customized with numerous upgrades. Among these are several Refinery Editions that I've purchased through Steve (@HEMIORANGE09) at MI Pinball Refinery as he does great work, provides outstanding service, charges competitive prices, and is a nice guy to deal with.