ThatZenoGuy
Residential Zealous Evolved Nano Organism
Item design - it's obvious a lot of effort was put there. Just the sheer amount of different items helps to make the world more believable. Some cool looking weapons, especially the handcrafted stitched together pipe guns. (shame they became useless very quickly)
Environment design (not level design) - a lot of cool looking locations and landmarks from Boston. (shame they were filled with cannon fodder)
Character creator (not character progression or character building) - a nice tool with a lot of capabilities. It's a testament that some people tried making their characters look like celebrities and politicians from the real world in the first weeks after launch at great success.
Weather and atmospherics - may not always be realistic but sometimes serve to create very strong apocalyptic moods.
Item design is FUCKED in fallout 4, everything looks like garbage.