XZ is a slog to compress and decompress but compresses a bit smaller than zstd.
zstd is quite quick to compress, very quick to decompress, scales to many cores (vanilla xz is single-core only) and scales a lot further in the quicker end of the compression speed <-> file size trade-off spectrum while using the same format.
Zstd and xz fullfil different needs. Xz take more time to compress and is faster to decompress as far as I know.
XZ is a slog to compress and decompress but compresses a bit smaller than zstd.
zstd is quite quick to compress, very quick to decompress, scales to many cores (vanilla xz is single-core only) and scales a lot further in the quicker end of the compression speed <-> file size trade-off spectrum while using the same format.