I have 4 recommendations.
ELvUI
If you’re already using this addon, then you might as well use it’s nameplate options aswell. I personally don’t use this nor know many people that do, but it’s an option if you don’t wanna get a new addon just for plates.
TidyPlates
This is probably the most common one across the player base. It’s basically just a small step up from the baseline to make them look better, but a lot of funtionality is missing baseline compared to some others, but it’s simple and easy.
Plater
Probably the one that is used most commonly among high level players. I personally don’t like the default look of it, but it’s major upside is the ammount of customizations you can make, and in that regard it blows the other addons out of the water, but the default setting leave some things to be desired.
KUInameplates
This is the one i use, and how good it is depends a lot on how much you’re willing to customize. The thing that made me stick with this is how good the default is. It will automatically color code mobs that are below 20%, but if you’re an execute class it will automatically color code the bars for your spec’s execute %.
Also it automatically shows all debuffs you can remove from a target and yours and only your dots or debuffs (looking at you default tidyplates).
So overall, if you want something simple go for tidyplates, but if you want something good that takes little investment, then go KUI, and if you want the best that requires more investment, then plater.