Which is better?

As long as you provide proper circuit protection on the output of the PW-ZW, it's fine to run your trains.  For TMCC/Legacy, just make sure the voltage from the transformer doesn't exceed 19V.

Along with proper circuit protection when using a post war ZW you will need to use a transient voltage suppressor(TVS) which can be bought at online electronics stores for about $3.00 a piece; 32 volt bi-directional.

Lee Fritz

1500W TVS diodes are less than a dollar.   These are the ones I use.  1.5KE36CA, 72 cents in quantity one, 62 cents each if you buy ten. Digikey shipping on small orders is about $3.

I want to thank you John and Lee for your responses some time ago. I was wondering how to set up these circuit protections and TVS diodes that you are talking about. I wanted to revive this discussion because I was testing the voltage on my Legacy loop (CW-80 powered), and the multimeter was giving me a reading of about 15 volts instead of 18 as it should be with the throttle all the way. Fearful of damaging the electronics inside with inadequate voltage, I wanted to run my Legacy engines with the ZW on a separate loop of track that I already what set up using that transformer, but I don't know how to set up these protective measures. Some diagrams would be helpful. Thank you!