Hello Susie,
All have something that sticks out, IMHO. Personally I like #3 best. Why? Although 4 and especially 5 look great, "SM" is associated out here in the Netherlands with what is known in English speaking countries as "S&M" (and not as in "Sales & Marketing"...).
I realise those are your initials, and I apologise if I sound offending. For what it's worth, in reverse I quite often have to warn my colleagues at work (US company) that they shouldn't abbreviate last names such as "van den Berg" to "vd Berg", even if it's common to do so in Dutch. It does occasionally raise an eyebrow in the English speaking world...
Thought I'd mention it, in case you're planning an international business
.
Good luck!