True Customs or are you referring to "Custom/Premium" calls?
Again, you'll get a ton of different answers. A good rule of thumb is to look at what the pros/guides use. Some would say they over pay, but when you're job/income depends on putting birds on the ground..., only the best stuff will do. That means premium calls like;
TG Super Mag, SMH's, Giant Killers, Zink SR-1/PC-1's. there are others, but these are all definitely battle tested and proven.
I'm trying a new Lynch Mob call from George Lynch (a past Michigan State goose calling champ) and had a lot of success with it so far. (my Super Mag and SMH are always on the lanyard though.)