here's my breakdown on this, leaving the big smith's out.
the 475 will do absolutely everything any of the 500's will, it'll just do it with better ballistics potential. to me, that kinda eliminates the 500's from my equation, i just don't have a use for them the 475 won't fill as well or better, plus the 475 is not only available in the FA 83, but in a sub 1K gun in the fine bfr.
now, on to the 454, to me, it's even more versatile than the 475, has even better trajectory potential. can shoot 250 grain bullets around 850fps up to 400gr bullets over 1400fps. it's the most affordable all the way around and will do everything still, the others will do. i can have great trajectory and low recoil with a great deer round and load up to kill elephant/elk and anywhere in between. to me, as i own both, i can see why some would favor the 454 and some would like and prefer the 475. i just think that the 454 is the most versatile and any of them will kill anything inside of 100 yards so i just like the one that offers me the best trajectory as i've made the commitment to get good with my FA454's beyond 200 yards.
one of the most muddy ideas put out in the last several years is that a 44 is good for deer, a 454 is good for elk and moose, it takes a 475 for a buff, and 500's for elephant, etc. nothing could be further from the truth. the 454 was killing, and doing so well and without question on elephants/buffalo/and brown bear. ALL OF THESE bigbores will and are capable of killing anything that walks, just don't be confused into believing that a 500 has an advantage on a 475 because it's slight difference in bore diameter.