Actually, this depends on the team’s maturity level. I usually prefer Plus-Delta method for newbie teams. I do not want to hurt their motivation by stating the negatives in the first Sprint which is the beginning of a long journey. When we approach issues as “went well” and “can be improved” they see that even undesirable situations can be addressed with proper actions in the next Sprint. In the following Sprints, where the problems become more prominent, I mostly use the Mad-Sad-Glad technique, because I find it very effective when sharing emotions. If there are too many topics to discuss and I observe disorganization among the team, I use “Dot Voting” to prioritize the most important issues and prefer to go over them.