Back in the day when the Sportsman's Show was the only game in town, I never missed it. Nearing the end, I stopped going because of the carnival barkers hawking their handy dandy non outdoors related junk. Although nowadays it might be difficult to discern what constitutes "outdoors related" because of ear plugs, marshmallows and shoe racks. These days, I only do the Spring Fishing Show but that might mostly be because of the high concentration of OFNers attending.
Edited to add: If I only had one show to pick I'd probably do the Muskie Odyssey in St. Catharines. If you even have just a minor interest in muskie fishing, then that is a must see. It is the only just muskie show with top speakers, great products, super auctions and MCI ensures that profits go back into the fishery. Good deal all around.