Sagiitarius and Virgo for both men and women. Aquarius and Taurus for men. Pisces, Capricorn, and Scorpio for women. 

Perhaps another question would be better placed as... What is sexy about each sign? Means you don't have to choose one over the other!

Scorpios. I just love their sensuality: the walk, the talk (they have such bedroom voices), the smiles, the eyes... I love their intensity and passion. I have strong Pluto in my natal chart.

Aries. I love their coolness and manliness! I have Aries on the cusp of my 7th. I'm instinctively drawn to Aries. They are simply sexy 

Leos. Love their confidence, their sparkling eyes, their great confidence and energy. I have Leo Mars and Venus. They just attract me with their simple presence.

As for women: my vote goes to Taurus (sooo sensual), Pisces ('cause I love feminine women), Libras ('cause I appreciate their aesthetics in general and they have style). I'm a Libra Rising with very strong Neptune in my chart, that explains my vote for Taurus, Pisces and Libra women

It generally seems that Aries and Scorpio (both ruled by Mars- primal, intense, sexy) and Leo (ruled by the Sun- confident, expressive, powerful) have the most raw sex appeal. 

Then Taurus and Libra (both ruled by Venus- sensual, graceful, aesthetic) and Cancer (ruled by the Moon- feminine, voluptuous, soft) are the most beautiful- particularly in women. 

Personally I find Aries the sexiest. 

So, attributes I kind of like, not thinking of it too deeply are; that aspect of girls sometimes in Cancer, but can be a lot of different signs. Where everything is intensely girly and becomes sexy at moments as well but you have to be quick to notice the change. It's like you can't escape from sexy. Either gender cancer seems fairly loyal to their gender roles and aware of those grounded elements of life.

Leo girls: Who have a natural confidence or some sort of vanity where if you give them attention they don't flip out, it's like... Well of course every man fanciess me that's just the way it is. Stop recycling old news... and they don't mind implying sexuality out of animal respect. Leo's I think calculate quite a lot based on animal respect.

Pisces can be sexy but it too often seems like you can't really enter 'negotiation' as such.

I have marvelled recently how few Libra or Aries girls I have ever met. Capricorns I have met never in a flirtatious capacity. If you send sexual energy to a Capricorn it often doesn't land and you are met with an unmoveable object of sorts in their brain.

My lips are sealed on Aquarius, Taurus and Sagittarius except to say this Sagittarius seems to do things in the extreme.

Scorpio and Virgo on raw physicality. Virgo with the dirty mind often.

Gemini girls are kind of damsels you want to save from themselves.

I didn't do guys. Guys are less fluid sexually in that way. I can't suddenly think what's attractive in guys.

Except of course. All Leo guys are intelligent, powerful and super sexy with ginormous dongs!