In 5e you don't "need items for a build." Have you read the DMG items? Very few of them interact with PC abilities in that way. Like in 3e you could do some neat things with expanded crit-range, and in 4e you were expected to have certain items to make the math work. But most items in 5e are more like, "huh, that's neat."
When players tell you what they consider fun, listen to them. But players also enjoy a bit of a surprise. So if a player approached me with a list of items they wanted, I'd observe their character for a few sessions and figure out which sort of items would be most useful to them. Then I'd twist the item in one of several ways:
1. The item is in the hands of a major villain. By "in the hands of" I mean "he's killing you with it." And by "major villain" I mean "you might want to gain a level or two before tackling this guy."
2. The item is cursed.
3. The item has some weird properties that are not what you expect. Like a magic bow that lets you cast
create/destroy water. Huh?
4. The item isn't quite what they want, but is similar. Like instead of a
+2 longbow you give a quiver with 20
+2 arrows.
5. The player finds a treasure map leading to the item, instead of the item itself.
6. Princes of the Apocalypse actually has a really nice quest (MINOR SPOILER ALERT) where the PCs find a fairly powerful magic item, and are then approached by NPCs willing to trade that item for an item of the PCs' choice. So that's a way to make the PC feel like they got to pick the item they want, but they still had to earn it.
7. When the PC is in a really bad situation -- like the party has been captured and stripped of gear, or the PC has fallen into an underground river and been swept away from the rest of the party -- that's when they find the item they really wanted.