No one mentioned the things I found important for hamburger success, so I will add some comments. The biggest problem with sous vide hamburgers is that they fall apart easily after being cooked in the water bath. Searing on a barbecue can be problematic because the patties break up.
To counteract this, avoid overly thin patties. In fact, go with very thick burgers, This suggests longer times in the water bath for the heat to penetrate, even if this has the disadvantage of promoting patty break-up. Most burger meat in stores is ground round, so it tenderizes well only over long cooking times. If you take it to 140 degrees it gets powdery, so keep the water bath at 131F. Use leaner ground beef to avoid break-up, and press the patties tightly while still at refrigerator temperatures. Then, never press the juices out of them after cooking begins.
Don't forget to do the things that make other burgers good when you cook them sous vide. Add flavor to them by mixing in good stuff before patties are formed: cheese, catsup or barbecue sauce, onions and garlic, spices and herbs; don't forget these just because you cook sous vide. Read up on umami. Use great toppings, great side dishes, etc. And remember that the patties are pre-cooked, so the time spent in the grill or in the pan to finish them should be short.
Answered by Leigh Jones on Monday, June 17