Thank you for reaching out to Geotab Forums. Your question is a great one indeed!
Depending on what you are doing in MyGeotab, what reports are you are running, how big the data sets are and so on, needed bandwidth will always differ. In terms of recommending we cannot suggest that because data usage and speed will vary based on this.
As long as you have a stable internet connection, MyGeotab should be able to work perfectly.