Once the v-cube is modded, most people think it's better than the Shengshou. However, it does take a LOT of modding and breaking in. If you're a beginner and just want a 6x6 to do a few casual solves on, go with the Shengshou.
I've heard the One Hand Zhanchi is quite good for one handed solves. Or, if you don't want to pay the extra money for all the mods done to it, you can just buy a normal zhanchi or a normal lingyun (I recommend those two instead of a guhong because they're slightly smaller than normal cubes and generally better for OH solves, but a guhong might work as well if you have bigger hands).
Well im not a beginner speedsolver, but only with 6x6. So of i get a v cube and modify it would it be better. Or should i get a shengshou first?