We recommend Gtechniq Crystal Serum Light + Gtechniq EXO v4. This makes sense if you're already in the process of coating your paint; just do your trim at the same time. If you're looking for a standalone trim coating, GTECHNIQ EXO V4 by itself is perfect because it has a longer shelf life. You're looking at 1-2 years of protection and water/dirt repellency.
Here's a good video: F10 M5 Detail Series: E13 - Cowl Cleaning and Coating - YouTube