The term "Best bets" has several uses in PRPC and in the developer community. At a high level, it indicates a subset of options that are likely to have the choice you are looking for. The system develops the list differently in different parts of the application:
Application Explorer
In the Application Explorer, classes most recently selected (up to 10) as a root of the explorer tree structure appear under Best Bets at the top of the autocomplete list. A Best Bet is a class in your application that is the Applies To key part of one or more rules. To view and select from a list of Best Bet classes, enter or select a class in the Application explorer and select one of the Best Bet options.
Auto Complete
You can configure an Auto Complete rule form so that the top of the drop-down list (under the heading BestBets) displays the results that application users select most often. The rest of the results are listed under the heading ALL. See Adding an Auto Complete control.
Report Editor
In the Report Editor, "Best Bets" is a tab in the Data Explorer, a feature that lets you quickly locate database columns with which to populate columns in a report. The "Best Bets" tab presents the properties of the class that the report reports on, the classes it inherits from, its indexes and associations, that have been used in other reports. If you are working in a new installation of PRPC (not an upgrade), and are creating the first user-created report via the Report Browser, the "Best Bets" tab may be empty. See Working with the Report Editor.
PDN
A few topics on the PDN are marked as Best Bets to indicate that they provide the most comprehensive and up-to-date overview of material about a specific topic. On the Search Results page, these topics appear first with a red Best Bet label.