I collect Assassin's Creed so this is a tough one. I have all the CEs including Unity, but I won't be buying the new one this year. Same for a LOT of CEs really.
If a game in the series is good, I'll buy the CE, I'll also buy the next game/CE in the series without question. But if one in the series turns out to be bad, I won't buy the CE for the next game that proceeds it.
I bought Total War 2, Battlefield 4, Unity, Hitman Absolution, Saint Row IV CEs - all because games previous to them were good. I haven't bothered ordering any of the new ones that are available as of now. I'll snap them up if the games turn out to be good, but otherwise that's how my process works.
It hurts at times because when a game does turn out to be good and I didn't preorder the CE, I often have to pay much more for it after release
