It all depends on what you're looking for. Generally speaking if you're single you're better off dating single women. If you're looking for fun and getting laid then it doesn't matter who you date. However, it's silly to stereotype and lower your chances of finding a good person. Just like not all blondes, brunettes, single women are created equal, similarly not all single moms are created equal.
Even as a single dad I've mostly only dated single women but based on my personal experiences these are the things that are not generally mentioned on SS:
1. Most single women, even in their early forties! want a family or at the very least want to get married. I want neither so you're either going to lie to her, she'll hope she'll change your mind and either you'll succumb or she'll move on. Most single moms are fine with never getting married again nor having more kids.
2. Single women expect you to give them all your time and attention, even when they knew from the beginning that you're a dad. For me (50/50 custody) this wasn't possible and kids always come first. Single moms on the other hand understand the challenges and are willing to not only work on the logistics together they're eager to actually help you raise your kid and want to give the kids the next best thing to their own complete family.
3. Single moms in my experience have had fewer sex partners. Surprise! Yep, you read that correctly. In fact, the avg was 2-4 guys and these are women in their mid to late thirties. I don't know exactly why this was but from what I gathered they were the committed, old school values type of women. Generally they married their high school sweethearts and stayed married for a long time (8-12yrs).
One of the single mom's I met was the most refreshing woman I've come across in almost 10yrs...ZERO games, very feminine, believes in traditional gender roles, she's financially independent, great/open in bed and wants to try all kinds of things, excellent cook, can sew etc...heck I tried to find reasons to keep my emotions in check but she's definitely one of those type of women who you rarely come across these days.
So my point is that if you're a single dad don't discount single moms because of one or two bad experiences. If that was the case I wouldn't date at all after all the bad experiences with single women lol