Which reproductive system is more complex, a man's or a woman's?
Without a specific definition of "complex" the question is very difficult to answer directly. In most important respects they are comparable in complexity.
By "complex", do you mean number of parts, or their function, or their arrangement? Or some other definition?
Both male and female reproductive systems have, more or less, the same number of parts.
The arrangement of those parts is a bit more efficient in the female body, as everything is grouped together, while in the male the vas deferens extends from the testes, hanging in the scrotum outside the abdominal cavity, up into the abdomen and around the bladder before connecting with the prostate.
But to call this greater complexity would be like describing a crumpled string as more complex than a straight one (they are both string...).