I had good luck in the past with Peak which I switched too after using BMW for quite a while. If you live near a BMW dealership the 5 gallon BMW DEF is cheap so I would just stick with it. If you don't then go with Peak. I bought some off brand DEF jug at the local O'Reilly's and within a few hundred miles my DPF was clogged and my X5 was undrivable. Now, this lead to me doing a full delete which was awesome and cheaper than replacing the DPF but still, with my new X5 I did my first fill with BMW (to get the trick bottle) but will go with Peak until I do the delete next spring-ish time frame.