Best Website for Train Schedules Around Barcelona

https://rodalies.gencat.cat/en/inici/

You mean commuting trains?.... Either http://www.rodalies.tk for RENFE trains or https://www.fgc.cat/en for FGC trains.

In case you are unaware, in Catalonia, there are different companies exploiting different train tracks so depending on where you want to go you'd take one or the other. Montserrat, for example, is served by FGC, Girona or Figueres by RENFE/Adif.

update Sam's URL is correct, it so happens that they have changed it so often these past years that I decided to create a short URL to avoid confusing tourists seeking info on these sorts of forums. In this way, I just update rodalies.tk when necessary without those that have already planned your visit having to find out the new one!