My overall favorite is Sagittarius, which contains a wealth of deep-sky objects and more Messier objects than any other constellation. B86, M8, M17, M20, M22, M23, M24, M55, NGC 6440 and nearby NGC 6445, NGC 6818, and NGC 6822 are some of my favorite DSOs found within the Archer's borders.
My second favorite summer constellation is Cygnus.
My favorite winter constellation, and second overall, is Orion.
It's difficult to choose a second-place winter constellation from among Canis Major, Gemini, and Taurus.
My favorite spring constellation is Virgo, with Leo in second-place.
Pegasus and Andromeda, in that order, are my favorites when autumn arrives.
As far as southern hemisphere constellations are concerned, it's a toss-up between Carina and Centaurus.
Sic itur ad astra!
Chance favors the prepared mind.
A man is a small thing, and the night is very large and full of wonders.