Present results of the best or the last iteration on dev set? Which is the correct way - presenting the results of the best or the last iteration on the dev set in a paper? In research papers I usually see only one value, is it the best iteration of all?

I'm asking because my model training last iteration wasn't the best one. Instead the best iteration was somewhere in the middle of the training.
Is dev set a validation set here? Your best model occurred where the error on the validation set was lowest. That's the model you choose. However the validation error will be a slightly optimistic estimate of the true generalization error. Ideally you have held out a test set as well, and evaluate and report error on that.