CLA: If you are solely a collector and student of the longrifle, I'd say the CLA is the one. I think all the builders, knife makers, horners, and a great showing of antique rifles. I ain't been yet, but plan to go this year.
Dixon's: If you are a builder and want to meet lots of vendors and builders and ALR guys, pick up parts or wood, or just ideas for your next build, Dixon's is the place to go. There are how to seminars from wire inlay to basic engraving, stock finishing to tuning your lock. Plus, there's a woman selling locks at the fair who will just charm a buck twenty five right out o yore wallet like it was greased.