You should usually expect lines at any booth that serves red meat, especially on weekends. These are the most popular booths.
1. Canada (according to WDW, Canada is by far the most popular festival booth)
2. Ireland
3. Australia
4. Hops & Barley (always check to see if the line on the left side is shorter)
5. Germany
6. Belgium
7. Craft Beers
8. Mexico
9. Argentina
10. France
11. China
12. Italy
Just as my own experience, I went to the following booths on Saturday evening because they had no line at all or a short line.
Morocco
South Africa
Argentina (they usually have a line)
Terra
Very short line on the left side of Hops & Barley. Huge line on the right side. Always check the left side.
Toward 9 PM, with a 10 PM closing, lines went way down except at Canada and Ireland. I don't recall checking Italy.