I really want a pair of spring fin straps. Slipping my foot into my fin and pulling the spring around it seems much nicer than awkwardly tightening straps. You only fit spring straps once, to buy the right size for your fit and fin. After attaching them, you get a perfect fit every time.
They're also really nice for anyone who does a lot of shore diving, where you don't always have the luxury of sitting down to put your fins on. Even when sitting down, putting on fins can be difficult.
For anyone buying a pair, look for the recommended straps for your fins, but don't hesitate to check if any generic spring straps will work just as well.