The Petzl Ball Lock carabiners are good in theory, not in practice. I work in the vertical realm, and have used many different auto locking carabiners. These are one of the most difficult to open with gloves on...the "ball" is tough to find even with them in optimum position.

The Petzl Am'D Triact Carabiners get a bad rap, but with a little practice they can be operated easily with one hand no matter which hand or orientation the carabiner is in.

I'm required to have double locking biners for work, after figuring out how to open the gate one handed no matter what orientation the biner is in, especially with gloves on (also required in my line of work), these are by far the best biner I've used. Like them so much that I bought a bunch of them for my recreational climbing.

I've got a co-worker that liked the ball-locks, I don't care for them, much tougher to operate with gloves on. After he saw how much easier the Triacs were to operate, he bought a bunch of those to replace his ball locks.

As for recreational climbing, lots of folks swear by screw locks, saying the Triac style gate will get dirty and start to hang up...to that I say they are not taking proper care of their climbing gear to start with if it gets that dirty. To each their own, people with smaller hands might have more difficulty operating the Triac, but my 10 yo Daughter has smaller hands than most with that complaint; she has no problem using them with one hand.

Of course they are a bit more expensive, but you get what you pay for.