You’ll have to use lightmaps if you want to achieve realistic results (for arch-viz). Currently, other solutions (vxgi, lvp) really can’t compete performance and quality-wise. Lightmass use photon mapping a bit like a mini offline renderer, just to bake the G.I. G.I is the most important thing in arch-viz. With the right settings and decent lightmaps it can look outstanding. You can try VXGI but imo it’s not worth it. It’s in alpha stage, it’s performance heavy, there is not a lot of help/tutorials about it and there are lots of glitch when you want to record a movie afaik. I tried it but meh, I can wait a lil more!
Once you start being comfortable with the lightmaps workflow, it’s not that hard. I personally use a script to auto-unwrap and flatten all object on channel 2, the lightmap channel and then export to UE4. In Ue4 you crank the settings. You can expect long build time but you only have to do it once!!!
My current project is pretty cool, it takes lightmass 4 hours to build lighting. My settings are pretty high, lightmaps resolution are high. I have 2 computers running through swarm agent to help the process. I record movies with my gtx 980 card which does have shadowplay. I can record at 4k resolution without performance hit. just read the forums and you’ll learn the workflow quite fast man! It’s worth it. Good luck