I've always hated the bag clips made of plastic that we bought at the grocery store and I recently tried a few promising candidates searching for replacements. These are my favorite! We only use them in the kitchen on bags, but I'm sure you could use these for other things too.
They're strong and I can't imagine them breaking, since they're made from a continuous piece of metal. They manage to both secure the bags closed really well, but release with minimal effort on my part. The plastic ones we used to have would always snag on the bags if I didn't open the clip enough before trying to slide them off.
They're small so when not in use they don't take up a ton of space. I had not considered size when hunting for bag clips, but I can now store them in a more convenient location in my small kitchen because of it. Even though they're small, the spring mechanism that makes the clip work is actually MUCH larger and stronger than it is on other clips. Usually it's a tiny metal spring attached to a much larger clip, and the metal spring does eventually break because it's so small. But I feel like these will last forever.
I like that they're sold individually, so I could just test out one to start. I came back and bought 9 more! I might get another 5. I got rid of every other bag clip in my house after I found these.