Rigol, Siglent, GW Instek, and OWON have the best 4 channel Oscilloscopes under $500. I go over features like bandwidth, deep memory, FFT record length, screen size, ARB generator option, digital decode options, and various other features. These are the top low cost full featured Oscilloscopes.
GW Instek link
https://amzn.to/2OomVE0
Rigol link
https://amzn.to/2CCmjG5
Siglent link
https://amzn.to/2UaWDum
OWON link
https://amzn.to/2JDtvHS
Top 10 Best Oscilloscopes under $300 https://youtu.be/PBLssdxZ15c
Owon vs Siglent Oscilloscope https://youtu.be/RgItGsjfPpE
