Really they all have strengths and weaknesses.
Major weakness, all except Daz's Anatomical Elements suffer from some degrees of mesh distortion when certain morphs and scaling are used on the underlying figure..
Otherwise it is all up to how well they are supported by both creator and other vendors, I can say from personal experience the three that I use the most are New Genitalia, Golden Palace, and believe it or not the Daz Anatomical Elements. (Which is actually not bad since it seems to get genital textures made for it, where others rely on sampling the torso or body texture which if you have genitals as part of the torso can cause some oddness depending on where things fall.) Another plus is Daz AE sre the only ones that can be sent to various game engines through Daz's Bridges.
Major downside to AE without third party support the morph ability sucks as it is almost non existent. But there are various 3rd party sets like Juicy Wet Cameltoe that expand that morphability greatly.
Now looking at 3rd party support I would say GP or New Gens are seemingly the best supported.
Saying all that though I can't discount Kitten's Genitalia as very well made, and very nice if you like meaty Labia Minora.
Kaluma's gens is nice as well, Sledgehammer's, Poison's, Powerage, etc are all good quality grafts, and really the major deciding factors is going to come down to again how well are they supported by original vendor and 3rd party vendors. So by that Golden Palace and New Genatalia for V8 are going to come out on top, with GP getting a bit more 3rd party support (Along with Meipe's other items in general)