I've been using GBoard for the last couple months after having used Swype for years.
As of today, I'm heading back to Swype for good (or as long as I can).
GBoard isn't nearly as smart as Swype. If there's a way to add to its vocabulary, it isn't nearly as easy or transparent.
Swype has its quirks, which is why I was giving GBoard a try for a while. But I'll take Swype's quirks along with its functionality.