Some of use don't have the luxury to use fingernails, or go to great lengths (no pun intended) to protect our nails only to find that not only do the products not work, they sound bad, and they break more frequently than our nails but take part of the nail with them.
I'm one of those people. My wife pleaded that I stop trying superglue with scotch tape, acrylics, and all the other online suggestions and I gave in when reaching into a backpack and half of my nail came off.
She bought me butterfly picks (wire) and I got a set of the Alaska picks. I knew that purists would argue that nails create the only acceptable tone, but I'd rather have another tone than not play at all, and fortunately I don't run into many purists that I want to impress.
My experience is that the Alaska picks are easier to get used to, harder to deform, and allow you to strum (as in flamenco style). They also sound like plastic picks, they are tight and my fingers turn blue even using the largest sizes, but my biggest complaint is that I have very large fingers and the picks catch on each other.
On the other hand, the butterfly picks take a little getting used to, create a bit of a metallic rubbing sound (a little repositioning can eliminate that) and they are easy to deform. By biggest complaint is that I discovered too late that I cannot strum except with my thumb. Not insurmountable, but a bummer. They create a very different tone than nails. I have heard use of the coated style or coating them myself with nail hardener would improve this but I actually like the tone. It is very different than nails but also very crisp and easier to play very loudly, allowing for a greater range. Given the choice, I go for the butterfly, but I have to get used to the strumming.