Making a choice to go for ZDB (Zero Delay Buffer) or NZDB (Non-Zero Delay Buffer) is fairly dependent on your application requirements.
With ZDB, we have a PLL inside that gives zero delay between input and output. This filters jitter present at the reference and has less jitter at the output in ps (Jitter can be minimal but never zero).
With NZDB, there is no PLL inside; it is just a Fan-Out buffer. This is not going to filter any jitter at the input and has a propagation delay.
So while making a choice, between in a ZDB and NZDB,
You select a ZDB if your source has a bad jitter that needs filtering and you require a Zero Delay between input and Output. You will also get variants with divider options to have frequency multiplications and divisions and also can adjust skew with ZDBs.
You select a NZDB, if you have a very clean source and need just fanout of the source with less additive jitter. However, your application should be fine with the propagation delay, the NZDB will have. You will have different options to match different signaling standards here.