This is always a fun thread, so I'll bump it with a response.
I actually thought for a pretty long time about my answer and I came up with some criteria that gives reason to my picks. I think it's difficult to state which toy I own is "the best," but I have a few contenders, some of which are fairly recent.
Sculpt and Articulation are huge factors for me, though if I were to add anything more due to my preferences in toylines it would be "Build Experience," which I think is broad enough to be applied to multiple lines. With that said, my picks are:
-Revol Mini Sengoku Basara Ishida Mitsunari: While I own both the larger and mini versions of this character, the mini has all of the essential articulation and a fantastic sculpt. The larger version is at times hindered by the amount of articulation it possesses and the joint style. The first figure I ever owned with articulated eyes and an astounding example of what can be accomplished at this scale.
-Amazing Yamaguchi Carnage/Harlet Quinn: it's tough to choose between these two but they both represent the best of what this series has to offer. Carnage has the insane amount of effect parts, a wicked and unique interpretation of the character in his sculpt, and of course, all the necessary articulation. Harley gets points for the unique nature of her accessories and optional faces, but also stands out as Yamaguchi's best female sculpt and maybe one of the better female sculpts across all of /toy/.
-VToys Robin: In terms of paint, articulation, sculpt, accessories, etc. this unique take on cyberpunk policing is just a smash hit. The quality of the fabrics is strong and articulation is relatively unhindered, though the fabric is fitted well enough that all resulting limitations seem understandable. Definitely biased due to my limited experience with clothed figures, but this is a great product.
(Cont.)