I have a couple of Buttons/Remotes around the house and the one thats the most reliable is actually the Aeon Labs Minimote, if you buy the old version [DSA03202 v1] you can have them for around ~ $20 USD
They are Z-Wave and not ZigBee and from my experience z-wave is much more reliable in my setup than ZigBee
they are not very pretty but they are small, have rechargeable battery and 4 buttons you can assign to different things/routines in Smart Things
The other ones I have are the Xiaomi Buttons and although these are a pain to pair, once paired they do work well, they are dirt cheap and esthetically more pleasing than the minimote