This one is too hypothetical to vote. Coming at it realistically along the arrow of time, I'd rather we rank 4th and be eliminated; I wouldn't know that that alternative time line existed. On the other hand, if I had a "one wish Genie" who offered me the choice to make one or the other happen, and I had trust in his/her ability to deliver: I'd go for the win at regional where the team would get the further inspiration of going to championships, and experience a great boost in marketability with sponsors. At CMP I'd probably stick with #4.
We were essentially in the 1B position this year; we were the second pick of the #2 alliance at Bayou and our alliance was victorious. The even better news was that we were picked by Breakaway and Wildcat for an unusual capability that we intentionally set out to develop; we decided that we'd rather be a good landfill robot that could get game pieces off the step and flip totes than a relatively poor HP station 'bot. We had only four seniors this year. Half of the team members (and nearly all of mechanical) were rookies, so we knew we had to keep it super simple, and play to ally with, not compete against, the top tier teams at Bayou. During eliminations, we tunneled to the step and delivered our alliance's #4 RC from the step to the vicinity of the landmark (has anyone used this term on CD?), scored totes, and brought in a pretty good HP noodle thrower to boot*. Had it been match play, we would have won most if not all of our matches by fewer points than our team scored; this does not count the 20-30 points our fourth RC enabled our alliance partner to score. If the trip to CMP had meant that we only provided a plate for our alliance partners' cheesecake, especially if our contribution didn't seem to make a real difference, I would probably have picked ranking #4 and being eliminated in quarters.
* Between 3937's HP and ours, we elicited the only "
noodle net" that I've heard was deployed. Each of them put at least one noodle over.