Active probes typically do better with high frequencies because they present less capacitive loading. It might matter in your application, or it might not be a big factor.
Low impedance passive probes also present low input capacitance, but they also have a low input resistance at low frequencies.
Active probes are preferred over low-z passive probes where the DC operating point would be disturbed by the low impedance of a low-z passive probe.
As a practical matter however if you are only testing the 50 ohm output of a 500 MHz function generator, no probe is required. The 50 ohm output should be directly connected to the 50 ohm input of the oscilloscope with a 50 ohm cable. Otherwise the slower DDA 3000 which supports both 50 ohm and 1 megohm inputs will be more versatile.