Waitlist interview.. chance of matching?

I would go to the program that you are more interested in. It really does not matter if you came off a waitlist or didnt get an interview during their first wave -- once you are at the interview, everyone is on the same level playing field. Remember that programs only interview their top applicants and there is no ranking based on who gets an interview. What I mean by that is -- if a program only interviews 50 of 900 applicants, there is no difference in their consideration of applicant 49 and applicant 50. You are all considered accomplished and something about your application stood out to them. Make the most of your interview regardless. It doesn't matter when you received it.

The process is more complicated that stated above.

Overall: list places in the order you liked them/you want to go to.

More in depth: Most, if not all, programs have some pre-rank order which is used to determine who they interview. Some programs put more emphasis on the interview than others but almost all use some combination of pre-rank factors (step 1 score, research, clerkship grades, location ties, etc) + interview performance (fit with residents, how well you answered questions, etc) to determine where you rank in the end.

I would still say rank based on only YOUR preference without trying to account for where they might rank you because the algorithm favors that.