VXGI gives the best result for dynamic global illumination–performance isn’t good enough for game releases but if you’re doing renderings that won’t matter since even if it takes a full second to render that’s way faster than using baked lighting or rendering in Vray or whatever.
Last I tried, which was for 4.6 I think, it wasn’t quite straightforward to build the VXGI branch, maybe it’s different now and following the instructions will work properly without having to go through the forum thread to find out what thing you need to change for it to compile successfully.