What sign and placements would be a good match for me?

Someone who has their Sun or Moon or Venus or Mars within 8 degrees of your Sagittarius Ascendant, or your Gemini Descendant. You don't give the degree of your Rising Sign (your Ascendant), so I can't tell you what range of degrees that would be (plus/minus 8 degrees).

If your Ascendant is very early or very late in Sag, then that range of +/- 8 degrees could include the end of Scorpio or the beginning of Capricorn.

You really DO need the degree in the sign, the specific place that planet was, in order to tell anythin.

Also, anyone who has their Ascendant or Descendant within 8 degrees of your Sun, or your Moon, or your Venus, or your Mars. By distance, in degrees.

Real astrologers do not compare signs in order to evaluate a match. It's the aspects, not the signs, that determine the quality (good or bad) of all the various interactions between two people.

Also, make sure that you also consider aspects that involve the other half of your planets (from Jupiter on out to Pluto) .. Saturn and the outer planets (when aspecting the "personal planets") can really screw up a good thing, and are best NOT ignored.

You have so much Leo in you.

Looking at your placements I would suggest only air or fire signs.

Edit: You mean AIR signs don't have enough depth for you. Fire signs are generally more deep than air signs.

I suggest pisces.