The main difference between the Geo-Redirect/Bot Filter as compared to the Redirection Rules is that with the Geo-Redirect/Bot Filter, you can set filters to filter out unwanted traffic so that this filtered traffic data does not contaminate your "real" campaign stats (whereas the traffic going to redirection rules will be logged as a part of actual campaign data).
The Geo-Redirect/Bot Filter takes unwanted traffic to a designated "safe page" and filters the clicks to a separate report outside of the main campaign stats.
Redirection rules are meant to be used for traffic that you actually want recorded as part of the campaign. You're just using different rules to monetize the traffic more optimally.
TheGeo-Redirect/Bot Filter also has an advantage in that it allows you to easily set the filters system-wide or to specific campaigns. You can easily switch them on and off when desired. They are more nimble and easily maneuverable.