I have shops on both, as well as my own website.
With regards to my experience I've made quite a few sales on Folksy, in the past 18 months, which has subsidised my sales on my own website, it has also helped with sales on my own site.
Etsy- I do have a shop but to be honest Etsy is so HUGE, especially in my field that you get 'lost' in the sheer scale. I will keep on with it, but really it's just to keep my hand in on there.
You do also have to find your 'niche' there is a lot of the same things out there, good customer service pays dividends,as does little extras like top notch packaging.
Selling online on a small scale is incredibly hard work, as Solid says, you have to get yourself 'out there', make the items, keep accounts, buy materials etc. Its really hard fitting it all in, as well as normal family life.
I wouldn't swap it for the world, but would like an extra 12 hours in each day