When it comes to functionality, CANoe from Vector is still the best by a long shot. But it is not cheap (multiple k€), requires the approperiate hardware interface and runs only under Windows.
It can do far more than only monitor. There is also CANalyzer, if you want to monitor only.
CANoe is basically the industry standard and if you have to work with car/truck OEMs or there suppliers, you have to have it.
For the cheaper option, there is
https://www.peak-system.com/PCAN-USB-FD.365.0.html?&L=1 for 245€
They offer a Linux driver, but the Monitoring application seems to be Windows only.
It also seems to be supported by busmaster so this might be an option.
Unfortunately, I'm no expert with anything other then CANoe, becaus that is what we use...