I've been to St. Louis many times. Was thinking of going tomorrow but probably won't set the alarm.
I don't know what you consider "better" but my honest opinion is that I would not drive from South East Michigan to attend. LOL!
Now that said, it probably is all in what you're looking for. It's not a specialty bird swap. It's just a rural, small animal swap in the parking lot of the local livestock auction house (that's what UPI is). They usually have a good turn out during the summer months (it runs once per month spring through fall) and I have met lots of people that drive a couple hours to get there. But you're not likely to find a rare something-or-other or anything like that if that's what you're hoping for. Lots of bunnies, lots of your common birds, a few nice pairs or trios here and there, some turkeys, usually some peacocks, ducks galore, generally some goats and the occasional pot bellied pig... If you have extra roos and you don't care if they end up dinner you can always unload them first thing for a couple bucks, there is a large family of asian descent (I think they're Hmong, but haven't ever asked to be sure) who buy them up like hot cakes.
So, I guess, in a nutshell, if you're looking for a higher class/priced specialty like sale, it's probably, overall, not for you. If you're just looking for a down to earth, swap of backyard pets with a few 4-H/small show animals and some ornamentals thrown in, you'll probably enjoy yourself.