well, I think it really depends on if ranma is capable of fighting at the same level as the inhabitants of the world he gets stuck in.
Obviously, a Ranma in Tenchi-verse who is incapable of wielding Lighthawk energy or anything comprable would only get his ass kicked by every space pirate, princess, and GP Officer in the galaxy.
Similarly, if ranma gets stuck in SM-verse, but it takes actual magic to harm the average MotW, and Ki does nothing, then he's equally screwed.
I did have to avoid Tenchi-verse though because of the other women in that series. None of them would really take kindly to his foot-in-mouth disease long enough to break him of the habit gently, well, maybe sasami once she's all grown up...
I also thought about A!MG, but the Kasumi-act-a-like already has a S.O. so ranma is out of luck there. Urd would never really be able to calm down enough and remain in character to win Ranma, and Skuld would treat him about the same as Akane, if marginally better.
He should be able to survive rather well in Fushigi Yugi or Samurai X worlds because they are a lot like his own power level, mostly skills based with a bit of Ki thrown in for spice. Yu Yu Hakusho is another world where he could survive rather well, so long as he can actually hurt the demons. He'd have to start learning how to use his brain for things other than combat, but he could survive.
Gunbusters... I just don't really see this as viable for some reason. true, it was many years ago that I watched the series last, but, I just have this image of ranma standing there facing the Gunbuster, then going squish...
I don't know the others to comment, so I'll STFU now...

GandalfTG