We use the quick links with our blue and gold. The really heavy duty ones, I think they are like a 2-3 inch one and we have to tighten them with a pliers. He so far can't unlock them if they are done with a pliers. He has started taking all the bolts off of his cage and destroyed the food bowl holders and popped a couple bars off the bottom grate LOL! Luckily he only has a week to wait for his new cage
Be careful using a key ring depending on what type it is. I definitely don't know everything about them LOL but I do know a few people have had their birds get their beaks and/or tongues stuck in the split key rings and many of the others are zinc coated. If you can find ones that aren't the split type and are stainless steel they should be great though!