Best would definitely be Nier Automata.
I preordered the black box edition as well as the PS4 digital solely for the theme, which is quite a chunk of $$$ to dump on a game I had no idea if I'd like or not. I hadn't played the first Nier, knew pretty much nothing about the series, and only had one loose online friend excited for it. But I thought the early trailers looked cool so I figured heck it and went for it anyway. (And vveerrrryyy nearly regretted the decision leading up to the launch, when all the dumb, gross 2B butt shit was happening.) In the end, though, it turned out to be my favorite game of all time and the best special edition of a game I've ever preordered thanks to the 2B figure (which I've since snatched up the matching 9S for), and the digital PO exclusive ps4 theme is one of my most used. That game was worth every damn penny.
Worst is FFXV followed by Xenoblade Chronicles 2.
FFXV not because I regret playing the game, but because I regret spending so much for an experience that let me down so hard. I got one of those super expensive special editions w/ the Noctis figure, and just... boy... was that game NOT worth that kind of money. Especially since it practically requires the DLC to feel halfway decent which meant I had to spend even more money on top of it in the end to try and redeem the experience. Shoulda just gone with the base version, man. (Fingers crossed I don't wind up with the same regret over FF7R lol.)
XC2 I went out on a limb for and got the special edition of as well (cuz, if it wasn't obvious by now, I'm a total sucker for those lol) and ended up hating the game and not even finishing it. Way too much jelly boob, panty shots, and Tora.