I think its kind of the go to as their products are just so easy to embed, their billing function is world class for start ups in my view. I think unless someone can compete on the fees and ease of integration, they will be the go to player for start ups.
Strip was our go-to choice as well, and I can't complain so far. Indeed, all the integration features are very well thought through, it's pleasant to use and their docs are clear.