Uhhhhh Aracth'nil, going for the prehensile route? :3
I think I like /my own/ bits like many have described it so far ...
Slit, very important :3, with ridges on the bottom ... I personally don't mind the barbs of Kindle's style, Raiden, but I rather like a more ... Sleek outer design. (So also no veins or so. Looks a bit odd :c)
Oh! Important addition related to my species? Bioluminescence ... It .. uh .. I think you may have already noticed the rather very prominent patches of fur on my back that can glow? ... Y-Yeah :3
And a light knot. Nothing very big or hard to fit in, but something to get a biiit closer
As for what I like to play with that's a whooole other story :3
Basically ... Anything goes, I'd say, as long as it isn't tooooo weird ... (Say, an ovipositor penis or something :E)