Yeah but I'm kind of a purist when it comes to burgers.
I use 75% lean beef mixed with 25% beef fat (probably 4 star - 80% if I'm buying it preground). I squish it between 2 pieces of cling film to make a burger. Salt before putting onto a hot grill & don't turn until the top starts to cook & you see a bit of juices pooling on top.
I believe the only reason to add stuff to the mince is to bulk the meat up. Seems silly when you live in a land with abundant meat.