UEFN editor offers a ton of quality of life improvements, but after testing building in both modes, I found that Creative is still faster to build overall (keep in mind that I have years of building in Creative, so I might be a little biased).
Seeing and working with UEFN, I realized 4 key areas that Creative is missing as well, and with those added, I believe Creative will be incredibly fast and powerful:
1)Prop search
2)Option to turn off the phone select shader and effect (in quick build menu)
3)Ability to lock a prop from editing with a button push, so you can select one inside it
4)World/local rotation toggle
Sometimes the workflow requires us to work within Creative, and other times within UEFN. With these 4 features, it will allow us to work in teams that share both modes equally, rather than having all team members wanting to use UEFN (mainly because of Creative missing those 4 features).