It all comes down to whether you have a neutral wire at the light box. If so, there are quite a few “3 wire” zwave options that will work well with SmartThings.
If you don’t, I think most people either use LightwaveRF (personally, I like that look, so aesthetic judgement is always individual) or one of the micros like Fibaro or Aeotec, as was mentioned.
Aurora is a newer choice, but has an official integration, so definitely worth consideration.
You can read more details and discussion on all these options in the U.K. Lighting FAQ. 