It's probably between Ratchet and Demon's Souls for me. I was just super impressed by that initial Ratchet gameplay reveal and how much was happening on-screen at any given moment. The amount of NPC's running around in the middle of combat, the instant rift hopping, the particle effects, etc. It just looks phenomenal.
Graphically, I think Demon's Souls might take the cake so far though. The lighting and detail in the environments is pretty insane. Plus removing the load screens all around is such a huge boon to a Souls game and seeing that in action was impressive.
Miles Morales also looks really impressive, but it's more of a known commodity (with loads of improvements though to be fair) compared to Ratchet & Demon's so I think those two top it for me for now. Could change by the time I actually play it.
I can't really judge Horizon FW too much yet because we haven't seen pure gameplay yet, but I'm sure it'll look mindblowing too.