What one should I use on my server?

Spigot is generally more efficient than paper, due to additional optimizations in the server software. It also gives users control over technical parts of their Minecraft server, such as specific redstone features to disable, TNT mechanics, and much more.

Paper also comes with a new "v2” timings system. This allows users to dive deep into the server's internal workings and can be very useful in identifying areas that are slow or lag.

Paper can also be used for Spigot bug fixes, making it more stable than regular Spigot. Both have a large user base and can therefore be considered stable enough for almost all uses.

Any server expecting to see even a modest player base should aim to be as fast as possible. Paper is an easy to use upgrade from Spigot. Minecraft crafting It can vastly improve performance with little cost.

After using PaperMC, my server still lags.

There are a lot of unique reasons a Minecraft server can lag. It can be caused by a specific issue, which users can easily diagnose via a timings report.