Many of Hacker News visitors would probably disagree. What most of us don't seem to understand is what Hacker News says is not the common statement of most. People here tend to be on the less design side of things, most on the can I use this entirely with my keyboard. Most of the population however is not like that.
I don't see any statistics that the average user has any preference over which button to use out of the 3 examples provided. I think most users would assume buttons are supposed to look like the sites/apps they visit/use most, amazon, facebook, google, instagram, etc. If you button functions similar to those examples your users would be happy.
Normal users tend to be "less on the design side" when it comes to actual usability. They might (or might not—I don't think most companies bother to find out) care that you came up with some hot-shit pretty design that impressed the VPs, but for UX the more "designery" your site the greater the odds it'll be hard for normal people to use.
[EDIT] which is to say I think a lot of application design hours/$s have more to do with cargo-cult "brand styling" from the marketing department, and internal promotion of a project + personal portfolio-building and design-insider signaling than with benefits to end-user marketing, sales, or usability. It's not all useless from that perspective, obviously, but I'm very confident a lot of it is.
> People here tend to be on the less design side of things, most on the can I use this entirely with my keyboard.
Wrong dichotomy. "Design" is not about the amount of eye-candy. Design is about how to make a product so that the user can use it most effectively. Making it visually appealing is an integral part of that, but only part of it.
I don't see any statistics that the average user has any preference over which button to use out of the 3 examples provided. I think most users would assume buttons are supposed to look like the sites/apps they visit/use most, amazon, facebook, google, instagram, etc. If you button functions similar to those examples your users would be happy.