I'll start by saying Halloween was a memorable movie for me and I watched it in the theater when it came out. I'm also a fan of some Japanese movies and anime, but I know nothing about Ultraman (and refused to let my two boys watch Power Rangers). That being said, here's my take on the two pins;
Art work: It just depends on which theme you prefer. I think Halloween has a better backglass and I love the clown, but UKR is more colorful and campy. Slight advantage Ultraman.
Armor: Ultraman wins for color and the cool Ultraman cutouts over the speakers. Halloween pumpkin cutouts just look weird.
Plunger: Knife handle looks cool, but what happens when it rotates? I don't know what that Ultraman thing is? I'm thinking that's what calls Ultraman, which is cool for the plunger. I like the way the knife handle looks better, but we'll say this is a tie.
Topper: Halloween 3-D knife stabbing the cab vs flat spinning disk, Halloween wins no contest!
Left-side toys: I love the look and detail of the hedges, something about the symmetry appeals to my OCD. But after seeing Ultraman in person, the buildings and monsters are really nice also. Tie.
Center scoop: Pumpkin is fine, but were pumpkins really a thing in the movie? Here again, I don't know what the Ultraman thing is, but at least I'm sure it goes with the theme. Winner Ultraman.
Right-side lock: Gravestone looks fantastic and very detailed. Ultraman pin just looks cheap. No contest, Halloween wins. Hoping modders can do better for Ultraman.
Middle playfield: I feel like Spooky put more effort into the chain link fence with the gate on Halloween, but the Kaiju under the car on UKR is really cool. Tie.
Upper playfield: No question Spooky spent more on the plastics for Halloween, the wood deck looks amazing! Also the details in the house; sofa, stairs (ramp), back wall with pictures just looks perfect. Ultraman artwork looks nice but the plastics look cheap again. Except for the jet (see next).
Extra Toy: Ultraman jet is so cool and totally improves on the upper pf. I've yet to see a decent pic of the Halloween knife over the launch lane. Winner Ultraman.
Video assets: I was totally sold on Halloween until I saw the Ultraman in person. Love the scenes from the show and how the screen looks like a retro display. During some modes the screen will shake which makes it seem even more integrated. As for Halloween, the one crappy video (so far) does not impress. Winner Ultraman (for now).
Sound effects: Not a lot to go on here, but I watched and played Ultraman and the sounds seemed fun and theme appropriate. I also understand there will be some callouts in Japanese which is just awesome! What little can be heard from the only Halloween video seems like a bad Loomis impersonation and some repetitive sound bites from the movie that could become annoying. I'm sure Halloween will be much better than what we've seen and heard so far. No decision.
In summary, I feel like Spooky put more effort (and money) into the Halloween toys, but Ultraman has great artwork, colors, video, and sound effects. Everyone wins!