IMO the best workhorse sans font out there right now. OFL or otherwise. I've seen people dismiss every such font as a mere helvetica clone but they all miss out on the steady incremental improvements that each of such "clones" offer.

Inter is carefully crafted. It is uncommon to find OFL fonts that are hand tuned to such a degree (kerning and hinting). It is a beautiful and subtly unique take on a time tested design.