Deliverance,As Arnicka points out, there are no reliable rules for which energies in a synastry are "stronger": it has a LOT to do with each person's birth chart and how the energies interact with the ENTIRE chart.
In your examples:
- mans venus (relationships) conj (energy is combined with) womans sun (self-expression, also dating)
- mans venus conj womans asc (self)
- womans venus conj mans sun
- womans venus conj mans acs
there are two basic relationship interactions: one with the self-expression of the person, and the other with the person themselves. In general, the conjunctions to the Sun will be VERY useful in dating and forming a favorable first impression. The conjunctions to the Ascendant connect one person to the other on a "personal" level. However, since the Ascendant is NOT an energy (unlike the planets), the result is simply a tendency for the Venus person to focusing on the Ascendant person. This personal focusing MAY be relationship enhancing, depending on what planetary energies are activated in the Ascendant person by this conjunction.
In short, people are complex, and each relationship (usually, unless there are twins involved! ) has its own unique chart. Interpreting people in terms of there ENTIRE chart will give the most useful information.
Urging complete chart interpretation,
Tim