All these guys are right on with their comments about the better LGB springs - the B’mann springs are definitely a weak point. I find that the Aristo H&L gladhands hang too low; they drag over crossings and closure rails at switches, and I have in the past cut them right off. The two ‘teeth’ molded into the bottom of AristoCraft loops, and intended to keep the hook centered, are also problematic; they can wrench a car right off the tracks at an “S” bend or crossover, and I shave them off entirely as well. Nowadays I only have a few Aristo loops here and there and none of their hooks.
What Mik says about having hooks at both ends is also true, but I don’t follow that practice and I’ve gotten away with it. I make sure to use cars equipped with hooks both ends for continuous, hassle-free running at shows, where the track may be set up on less than ideal surfaces and where for the benefit of youngsters I want the train to stay together for sure. On double-hooked cars, The credit card gizmo works great, BTW. I use a thin plastic spatula given me by a fellow clubmember myself. All the same, on my own backyard pike and switching layout I stay with the polarized cars - a hook on one end only - because a single uncoupler ramp will operate the polarized ones and because novice operators can manage these couplers with their fingers alone. Your trackwork has to be pretty good to get away with the single hook, though, and I can say this practice hasn’t caused me any trouble. Like other writers here, I prefer the tougher and more durable LGB springs.
I chose hook and loop couplers for their reliability and ease of operation for novice operators. Oh, and all the readily-available knuckles at the time seemed grossly oversize and had a tendency to sag… The knuckle coupler situation has improved somewhat since then, BTW, but I’m very happy with my H&L’s.