Most people will be familiar with RS-232 when connecting to a computer (COM ports). In the industrial/embedded world, it's still used quite a bit to connect to devices for logs/terminals/programming and setup etc. Of course now we rely on usb-serial adapters to connect them to our laptops.
RS-232 is still used for connecting to some embedded chipsets. Best example would be modems/4G modules. You can pick either RS-232 or USB, however sometimes on that little microcontroller you're using it won't have USB. If you don't need a huge amount of throughput then the serial port is fine.
RS-485 as others have mentioned is great. Often you can't run new cables for cat/fibre so you're stuck with stealing some copper off an old system that has been decommissioned. You'd be surprised how far you can run a RS-485 system at low speed and maintain high reliability.
RS-232 is still used for connecting to some embedded chipsets. Best example would be modems/4G modules. You can pick either RS-232 or USB, however sometimes on that little microcontroller you're using it won't have USB. If you don't need a huge amount of throughput then the serial port is fine.
RS-485 as others have mentioned is great. Often you can't run new cables for cat/fibre so you're stuck with stealing some copper off an old system that has been decommissioned. You'd be surprised how far you can run a RS-485 system at low speed and maintain high reliability.