Trine is the best position you can get. Unfortunately you can not get all of your signs 100% Trine with someone, or at least I have yet to see it. Trine is Leo with Aries or Sagittarius, but not Leo with Leo. Leo with Leo would be Conjunct, a conjunction is like the 3rd best position you would want. Sextile is the second best, but Semi-Sextile would be fourth best… Berlin wall if you will. Opposing along with Conjunctions are truly the last position I would consider. Fire and Air together, Earth and Water together; any other exceptions are really inadvisable. This is in looking for a partner or friends, not looking at aspects in you own chart; that is different.
The trine(120°) is the relationship of one sign to those four signs away from it on the wheel(such as Aries to Leo, or Aries to Sagittarius), and the sextile(60°) is the relationship of one sign to those two signs away on the wheel(such as Aries to Gemini, or Aries to Aquarius). Both the trine and sextile are considered as non-critical or secondary aspects because of their generally easy or free-flowing natures. This however, does not make them any less important than the first group. It would be like saying that the signs of Gemini and Aquarius (representing the sextile) and Leo and Sagttarius(representing the trine) are less important than Aries and Libra(representing the conjunction and opposition respectively) or Cancer and Capricorn(representing the square). In astrology no one sign is any more important than another and therefore neither should any of the aspects be either.
A trine (abbrev. Tri) is an angle of 120° (1/3 of the 360° ecliptic), an orb of somewhere between 5° and 10° . The trine indicates harmony and ease. The trine is a source of artistic and creative talent, which is innate. The trine has been traditionally assumed to be extremely beneficial.