Played both.
Themewise Alien is winner for sure. It really pulls you into Alien world.
Built quality wise DI wins easily. The cabinet may be strong with Alien but the built under the playfield didn't impress me at all and the one I played already developed several issues. Hope-think they will be solved however befor mass production.
Given the fact that Alien (with previous per order pricing) is also a couple thousand euros cheaper over here Alien wins it for me but that doesn't mean that DI is a bad pin !! It played with a good flow, many shots, animations on display are well made but not my taste, the selfies is great fun !!
So at the end of the day you can't go wrong with either of them.