Side-release buckles are the traditional plastic snap buckles you've seen on backpacks and life jackets. They're proven, reliable, and keep your helmet securely in place when properly fastened. The main downside is that they can be frustrating to operate with thick ski gloves—you'll often find yourself fumbling to line up the two sides and snap them together on a cold lift ride.
That said, side-release buckles work perfectly fine for most skiers. If you're on a budget or only ski a few days a season, there's no safety reason to upgrade. Just make a habit of buckling up before you put on bulky gloves, or practice the motion so it becomes second nature. The real advantage of magnetic buckles like Fidlock is convenience, not safety—both styles keep your helmet secure in a crash when properly fastened.