Paper is a fast and effective way to use plugins, its also usefull for plugin developers as of its easy way to add and remove plugins. Paper allows most plugins to do as they need. It also doesnt take much memory or RAM so you can run it on small servers.
Additionally, Paper can handle alot of plugins for bigger servers so you can have small servers with not as many plugins, or huge servers with hundreds of plugins. With Paper you can do almost anything in minecraft.
If this is not your style however, and you want to play without plugins or with mods, then you can use Forge and Fabric for modding, if you don't want to use plugins or mods then Vanilla is a stable option.