I put an asterisk in front of recipes I really like.
Example: *Wild Water IPA
Rating your recipes with numbers 1, 2, 3, etc. in front of the names would work as well.
Example: 1 Bob's Pale Ale
2 Lovely Lager
Either way would bring these recipes to the top of your list(s) when sorted by name. Numbered recipes would even show up in numerical order.
Another alternative would be to create a new folder and name it Favorites. As with many other functions, BeerSmith allows you to customize lists.