...Personally I would support Yukari, for her craft is way better than him in the same field, and most likely just going to pull something even more absurd than him. Plus, a normal person like Rick can't escape from her eyes in the first place, and would have his information pry open.
Edit: Full explanation for anyone of interest ( and because I'm bored)
Firstly, in term of ability: While Rick have inpressive amount of abilities and even capable of destroying universe, all of it come from his gadget. Which mean any alteration of it would mean it deactivation or even backfired, the skill in which Yukari is especially good at. Speaking of which, her ability to manipulate boundary basically mean she got the universal remote, in all of it sense, in the palm of her hand, and it's not something Rick could steal or seal away with. Her ability work extremely well against human ain't going to help him either.
Secondly, in term of intelligent: Yukari's knowledge of the boundary basically mean she's already more insightful to the nature of the world (A.K.A science) than Rick ever achieve. Even if you count brain power (which I doubt he have one), she could calculate even the depth of the Sanzu river (a thing that's know to be unknown in width), capable of doing equation of thousand variable in seconds, and control a nine-tailed fox, which in myth would be already smarter than him. Not to mention she could ram it up further with her boundary manipulation.
Thirdly, in term of ruthlessness: If Rick is a drunken sociopath, Yukari is the Great Demon Lord. She's always have many scheme that she couldn't remember which one, unlike Rick that thrive only through ad-lib and doing it on the go. Their attitude is like a child that's facing against a Youkai Sage, meaning that she would always have him in the palm of her hand.
And not to mention her based stat is already more superior than him many time over...