@Kaduufrrj Yeah, the size of the crab definitely has an impact on the mess factor. There are so many types of crabs around the world (from the tiny crabs used as snacks in Asia to the large Alaskan King crabs you mentioned), but smaller crabs are definitely more of a pain to eat given the amount of meat that comes out of it. Larger ones, while they have thicker shells and require a crab cracker or have long legs where scissors are more useful, aren't usually as messy, and often Asian restaurants will chop it up before they cook it so that it's easier to eat and there's more surface area to catch sauce on.
Mentioned in the comments are blue crabs from Chesapeake Bay/Maryland in the US. Smaller crabs. When I went to visit an American friend who did a crab boil, the method they taught me was to take off the top shell and then take the rest of the body in both your hands and break in half. Pick out the meat, eat the innards from the top shell (or dip the meat in the creamy innards), and even lick off a bit of the Old Bay spice from the shell. I was mostly sipping on a bottle of beer and eating a lot of the sausage, potato, corn, onions, and shrimp from the rest of the boil in between picking out the meat. We had a lot of crab left over in the end because not everyone wanted to break them down. Messy and a lot of work, but I think the fun is in the shared experience with a group of people.