I've done both SW & LCHF and can honestly say that for me it's LCHF hands down.
I was a SW member for over a year and lost probably 1 stone in that time due yo the "yo-yo" effect. Now, that was my fault not theirs, but I didn't find the support they offered very useful.... it was basically " try harder". The thing that got me was that they had a table selling a whole bunch of stuff that they proudly promoted as low fat - which it was..... and loaded with sugar, and there was never a shortage of people buying it..... me included! I also decided that paying £6 per week to get weighed was a bit silly as I have a set of very good scales at home
I also found that after class I have having a "treat" meal as I had a week to get back on plan.... which didn't always work!
Now, that said, I believe that the clubs have a great deal to offer some people - it's a very weak kind of group therapy, and it's constantly evolving - and now includes low carb if I remember. One of my friends has lost a massive amount of weight with SW and has reached the "Woman of the Year" finals, so it can work.
As ExD said, have a look at dietdoctor. I did the 2 week challenge and loved it. I also find the support here great... it's like a massive club meeting... but every day