Of the listed options, my favorite form is her as Princess Lady Serenity. I love her both as a princess, but also grown up. I'm much more interested in her destiny than that of her mother.
My actual favorite form is a form she never taken on in the series, but presumably will, is that of Queen. In my younger days, I called it Queen Serenity III, but I am not sure what her canonical queen name would be. My second favorite form would be her as an adult Sailor Moon.
I had never heard of "Sailor Chibiusa Moon" and right now, I am intrigued by it.
I love Princess Small Lady Serenity, as I just love her in her Princess form. I love both the anime dress and the manga dress. I just love the grown up version more.
I love base Sailor Chibi-Moon, though, in just about every incarnation. I love the color scheme and I love her character in this juncture of the arc.
Black Lady is cool, and easily one of my favorite characters. She ranks just a little below Chibi-Moon though, mainly because of the whole incestuous desire for Mamoru (something the old anime wisely downplayed). She's still awesome.
I have no opinion on Parallel Sailor Moon Chibiusa because I haven't seen much art of her.
I actively dislike the Super and even more so the Eternal upgrades to her outfit. I dislike them all around. The Sailor unit is iconic as it is. Changing the color scheme or adding different layers and accessories is just awful.
Base Chibi-Usa is my least favorite, not only because she reminds me of all the horrid actions she took when she first arrived, but because her pink hair, while awesome, doesn't go well with normal clothes. She looks better as a princess, a Sailor Guardian, or even a villain. Sticking a girl with her iconic hair in outfits so mundane is criminal.