For me, I prefer videos over images, but really it's only because of my shitty tastes towards ryona as a whole.
Images can work better for me depending on how more sensual/sexual it is rather than the ryona situation involved. If it shows more skin, has nudity, or put in a position/pose which shows off their body in a certain way, then it can be easier for me to get into. Because of this stupid mentality, I would say the majority of most ryona material out there becomes lost upon me, so I miss out on what most people appreciate or would find entertaining in general.
Videos are easier for me to get into than images, but much like images, it still has to follow the same rules more or less as above. Seeing the stuff in motion can be more amusing and easier to get into than seeing a picture of it for me and I think that is mainly due to my major lack of imagination that I can take from a single picture. Honestly, I think I'm more towards the sensual/sexual nature and aspect in possible ryona material than the... well, ryona nature of ryona. Most of the time, it's not what is happening to the victim, how they get defeated, or the end result, but rather if there is titillation involved that I find appealing. Call me a phony for having somewhat of a semi-fake interest in ryona because that's kind of how I see myself on the interest.