The Monsoon dress is nice but the lace overlay looks very "scratchy" in the picture (it is no surprise that it is made from nylon and viscose). Might be quite different on though. Haven't impressed with Monsoon fabrics at all in recent years.
I would go for the DVF out of the two. I think you'll get far more wear out of it - that monsoon number will snag so easily. While that DVF style has been very prominent in the last few seasons, it has actually been around for decades. Done well (I think the DVF is) it will not date too quickly.
Have you tried Hoss Intropia? Their "lace floral dress" comes in 4 styles and black or Ivory. The back bow version is just over £200 and I think it looks far better than the monsoon dress.