simple question, but surprisingly tough to answer,

I have some ideas of choices, but none of them is perfect:
1) batch processor in Reaper (slow, cannot use cpu multi-threading in batch jobs afaik)
2) batch converter in SoundForge (Sony sold it, Magix bought it, future is unknown)
3) app by Aurchitect called Myriad (there were some ownership changes in company, and I feel it's not working 100% reliably)
4) audio converter in AIMP4 (Windows-only app, so needs to be run via something like Crossover, so not an elegant solution)
5) app Format Factory (again Windowws only, needs non-native environment to run on MacOS)

any thoughts and personal recommendations?

 

What do you want to do with that,please?

 

various enterprise-grade batch format converting, wav, flac, mp2, mp3, mp4 audio layers, cue sheets, usually smaller files of short duration but bigger batches,
last time the batch render in Reaper took roughly half day, in Format Factory on Windows it took roughly an hour on 12-thread cpu

 

Foobar2000 can parallelize every file into one thread, making the conversion very fast. You can also use command-line encoders with your own parameters through foobar.