You may have to be a little more specific in your requirements.
The Hue switches are very reliable and work great, but they don’t work directly with SmartThings (or aren’t reliable in that use). But if you just want something to control devices connected to Phillips hue bridge, they’re great.
Lutron Picos are extremely reliable, but again don’t work directly with SmartThings. If you only want them to control the Lutron master switches, they’re perfect. There are other ways to get them to control other kinds of devices, where they are reliable, but I suspect the set up is not as simple as what you would want.
I find the logitech Pop buttons work well for us, but I know some people have said they were not as reliable for them. I suspect it’s a question of where they are placed in relationship to their bridge. They do have an official SmartThings integration so they do meet the “works out of the box” requirement, but they are a lot more expensive than most of the other buttons.
The Sylvania dimmer switch when used with the stock DTH will act as a two button switch and work straight out of the box with SmartThings. Reliability reports on that one are good. It might not be the form factor you want, though.
So there are a number of different options, but it depends on exactly what you wanted to do.
I assume you’ve already looked at the buttons FAQ, but I’m just going to put it here for others finding this thread in the future: