Earlier this week, Node.js 10 entered its active LTS phase. This means Node 10 is now considered stable and suitable for general use.
We've been routinely testing Node-RED against Node 10 since April and have never hit any node-specific issues in the core.
There are however some reported issues with 3rd party nodes - such as Upgrade Node-Red - sqldbs install error. Hopefully those nodes will get fixed - with Node 10 being LTS, it is entirely reasonable to expect well-maintained nodes to work on it.
From previous experience of major version updates, the nodes that are more likely to have an issue will be those that include some binary component that needs to be compiled. The vast majority of nodes will be absolutely fine.
At this point in time, for most users, we still recommend Node 8 LTS as the preferred version for use with Node-RED.
Node 8 remains in Active LTS until April 2019, where it will enter Maintenance LTS until December 2019. More information about the Node LTS schedule is available here.
If you choose to use Node 10, then please exercise a little caution. If you do hit a problem that is related to the version of Node (most likely an install-time issue), then please check the node's git repository for any known issues. If there isn't one, please raise one. That's the only way we'll be able to keep things moving forward.