Both should work fine, but we always recommend streaking onto agar plates first. If your stocks are contaminated this will often be visible on the plates but very hard to see in broth. Furthermore, if you are counting on doing growth assay and comparing growth to for example a mutant strain, or if you want to do some kind of gene expression analysis it is much easier to synchronize different strains when starting from single colonies.
As personal opinion and experience it is always preferred to go for streaking method on agar plate instead of directly inoculates them in broth. The rationale behind this is to avoid the enrichment of contamination if already in the glycerol stock. To revive pure culture you first streak the culture on agar plate than take well isolated single colony and inoculate in broth medium. Thus the revived culture will be pure.
Souce: NovoPro 2018-03-22