I prefer The Force Awakens. Seeing Rogue One twice now, I do like it more than I did during the initial viewing, but the first half of it still kind of slogged along, while The Force Awakens' pace feels very well balanced to me. Plus I liked the two new leads in TFA than I did R1's, which turned out kind of dull. I also would've liked Jyn more if there wasn't a *ahem* forced backstory, I'd have liked her to have been more of a random criminal turned hero. I felt her story just bogged things down.
Had it been a vote for individual scene from both films though, Darth Vader's at the end takes the cake, easily, no question.