have always preferred straight barbell curls because they're harder to do than cables imo
people always say they get better isolation with cables but thats because they're form is poor with barbells.
slow negative, explosive positive, squeeze at the contraction in good form with heavy weight, drop sets you can't beat barbell curls imo because i think the resistance on the negative is harder than cables.
probably due to the difference in mechanisms of the weight - cables attached to a stack and weight directly on a bar.
ancillary muscles more involved too.