I use V4 and M4 extensively so i can only really comment on eyes for those figures.  When I buy a character almost the first texture I change is the eyes as it seems very difficult to find a character where the reflections are not burnt it. 

In addition to those already noted here, that I have used, one of my favorite collections is SG Realeyes by Surreality.  It has a number of options for the build up of the eyes and all its parts.  They are still available at Daz for the same price I paid in 2011, just be sure to search for Realeyes, with no space as the search does not find them if there is a space.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.