Most players can start with Forever's default nameplates. If you tank, try Threat Plates. If you want full control, use Plater. Blizzard's notes list nameplate fixes on the default UI, including Elite status and clickable debuff icons, so give those a go first.

Add-on What it does Best for
Plater Highly configurable plates with cast bars, threat colours and debuffs People who enjoy tweaking
Threat Plates Colours and sizes enemies by threat, with role-aware defaults Tanks, and working well out of the box
BetterBlizzPlates Blizzard's plates with extra features Keeping the default look
Simple Quest Plates Shows quest progress on enemy plates Levelling
Tepiuz Threat Threat readouts on the default plates Threat numbers with a default look

What Forever hides from add-ons

Threat Plates' changelog says its threat delta and tank value options are turned off on Forever, because threat values are secret to add-ons there. Threat colours aren't listed as affected, and we haven't confirmed that on the live game. So an add-on that shows exact threat numbers may not be able to do what it does on other versions.

NameplateSCT

NameplateSCT had no Forever file when we last checked. Don't force it to load.

Don't run two at once

Two nameplate add-ons fight over the same plates. Turn one off completely before you try another. We've also compared Plater and the default plates.