The thing is that everyone's reasons and choices are different and even the reasons why they might make those choices. Also, my reasons don't necessarily reflect on what I think of someone else's but they are still my reasons, iyswim. so in my case:
Going it alone:
With a sperm donor? absolutely not because I personally have moral objections to sperm/egg donation. Again, what other people choose is their choice, but it's not something I would ever contemplate.
Had I found out I was pregnant and the relationship ended then yes, because I could never terminate a pregnancy. But I wouldn't choose to have a child as a single parent.
IVF:
No. It was something me and now xh talked about when we were ttc dc2 and for me it was a rollercoster which I could see that once you started would be difficult to stop. If I could have been sure I could say that e.g. we would just have one round and stop at that then perhaps, but then I was faced with the possibilities that i might have more embrio's than for just one round, and could I stick with my decision and destroy those after one round? I didn't think so, so in my case it wasn't for me.
Adoption:
Perhaps. again, when ttc dc2 we talked about it briefly, but as I am VI the reality is that I would be unlikely to be allowed to adopt in this country, and therefore it wasn't something which we could ever give serious consideration to.
Surrogacy:
No. Again, I have some serious moral issues with surrogacy and all that entails. Again, whatever works for others is their thing, but it wasn't something I would ever even consider. Equally I would never be a surrogate for someone else.