Hi! what is the best character creation software out there? it can be a paid too.
Depends on your skill/time . Do you want a 1click solution to create generic characters with no personality? (good for prototyping phases) Probably daz is then a good choice.
Do you want to spend weeks and weeks on one superhighquality hero character with proper design? Zbrush for sculpting, Mari / Substance / Photoshop for texturing. Maya for assembly, rigging and animation.
Then theres is also a whole bunch of smaller more specialized softwares and plugins to do whatever else smaller task you need to do.
PSEdit: adding Marmoset to the texturing bunch is a good Idea, ive heard only good things about it, and someone now made a seamless Marmoset to UE4 exporter for fully functional PBR shader imports.
Oh thanks! <3 will check these things out 
If you already have a main 3d modeling program you can always use makehuman to generate some base mesh.
3D scanners 
Well here I go again sounding like an ad.
The grand daddy of grand daddy of all character creators not specific for the purpose of video game development, and in my opinion, is the Genesis 3 framework as part of the Daz Studio product line that already covers everything that more recent applications promise to do off the shelf as to fit to finish requirements and has been doing so for years.
What you can get to start is the basics as to kitting up as to required applications for free, in this case Daz Studio, as well as both male and female Genesis 3 models, for free, and then you can buy what you need when you need it that does not included a bunch of stuff you don’t need.
The down side is you don’t get the app to app convenience of a solution made to plug into UE4 with ease and does require building a pipeline work flow from A-B but doing some of the work load as to usability you can save a ton of money as to were your character design has to be a year from now rather than something that works today which in most cases is what your paying for.
But can you import your own character base model?
This page looks very much like Make Human, which is limited to their awful looking model.
Maker of this plugin was leader programer at makehuman.
you cant import your own base model for now.
there are 15 base mesh(model).
I am searching a program too.
@FrankieV
Do daz 3d have breast rigs ? I remembered your video has spring joints at breasts but did you added them or they comes build in ?
They are built in along with 75 joints for facial animations.
There is also Poser. The most current Daz models are not set to work with Poser, but you could put the leg work behind it rework the models to make them work with Poser (which is my plan). Also, I think Poser is a lot more export friendly for game devs.
Adobe Fuse is free so far, it outputs to Obj. Mixamo has free rigging for Fuse.
Also, you can get animations for your characters from there.