I've seen a lot written about synastry, and I've experienced a lot. I don't necessarily find the most common "hot takes" to be representative of my experience, and so today I've come up with my personal list of the underdogs and over-rated aspects in synastry. You can learn more about my thoughts on synastry aspects and which ones are the most relevant here.
The over-rated aspects
By FAR I think this is the most over-rated aspect. Researches have shown the only relevant aspect between these two is the trine, but by experience, this has been a wildly disappointing aspect to have and did not indicate chemistry one bit. It does have a push/pull type of dynamic but not necessarily so a pleasant or fun one.
I haven't been impressed by that one either. There is for sure a good capacity to like each other and have similarities that are nice to have, but to me this is one that's wildly over rated and absolutely not necessary to have.
3. Pluto - Mars
Supposedly, Pluto-Mars is the promise of wild and untameable sexual chemistry. One that you remember for decades to come. Well, I've had the double whammy and unfortunately, the legend did not live up to reality. Pluto and Mars CAN show up this way sure, it can also represent simmering rage, power battles, and inflexibility.
4. Pluto - Venus
I haven't experienced this one besides a Pluto sextile Venus in synastry, but I would go on a limb and say that all Pluto aspects in synastry have a tendency to be over rated. I'm not Plutonian so perhaps I'm biased, but I find synastry to be much more enjoyable without excessive Pluto.
The most under-rated aspects
Mars - Mars
Now as much as I found Pluto - Mars to be absolutely non conducive of chemistry, on the other hand, Mars - Mars aspects are rock and roll. I had the square and opposition and enjoyed it a lot. It does give as well a tendency to bicker and fight, so depending on your personal composition, this is a hit or miss. If you're someone who enjoys a challenge, this is a winner. If you hate arguing, best to skip that one.
2. Mars - Moon
I have had this one in all flavour, harsh and soft. They're always a winner. The harsh aspect also create hurt and insensitivity, but nothing that can't be worked on through conscious communication. This is a highly sexual synastry aspect, no matter if soft or hard aspect.
3. Moon - Moon
This one truly is a winner as well, with a preference for the conjunction personally but even the square has shown to be quite under-rated. I also shared a progressed Moon conjunct a partner progressed Moon, and it created similar energies to a Moon-Moon conjunction through birth charts.
4. Neptune - Moon
This one is a sweet, sweet aspect, but it can lead to platonic relationships if there isn't enough fire elsewhere in the relationship. Neptune in soft aspects but also harsh to some extents to Moon is a really sweet aspect that promises unconditional love and forgiveness between two people.
5. Saturn trine or sextile Sun/Mercury
This one is really nice as it promotes a natural respect for the partner. I haven't experienced that with the conjunction but this could have been just a one-off.
Juno conjunct or opposite is an aspect that indicates strong compatibility with a mate. I read it in the research I mentioned here and experienced it in synastry, and I did find it to be a really under rated aspect in common Astrology culture.