>>23455164
SNES is harder and requires more thought, especially when the Shocker Riders appear towards the end of the game, but it's more basic I'd say.
Shin is easier and feels more like a flash game at times but if you're on Master difficulty the bosses are a test of patience and dodge timing because a single hit is like 40-70% of your health depending on the attack, they have super armor which takes a decent amount of time to chip down even with burger drops and upgrades, and they have mooks interrupting you. Ichimonji and Rider 0 have fake out attacks. It also gets easier the more upgrades you get on both your character and on the Cyclone since a maxed out Cyclone can start you in area 1 with four buffs, a bunch of sodas, and buffs to your special attack.

I played through the JP version when it came out but got a Switch 2 and finally got off my butt to play the English version with the DLC I bought ages ago. Ultraman is pretty lame, Unit-01 is a nice middleground, and Godzilla is just great. If you get it now you have to pirate the DLC, it got delisted.