Here it is, the books that the Avocado loves the most:

1 The Lord of the Rings 13 mentions
2 Slaughterhouse-Five 10 mentions
3 Jonathan Strange & Mr Norrell 9 mentions
4 Cat’s Cradle 8 mentions
4 Catch-22 8 mentions
4 Harry Potter 8 mentions
4 To Kill a Mockingbird 8 mentions
8 1984 7 mentions
8 The Hitchhiker’s Guide to the Galaxy 7 mentions
8 The Hitchhiker’s Guide to the Galaxy series 7 mentions
8 Moby-Dick 7 mentions
12 Discworld 6 mentions
12 Watchmen 6 mentions
14 A Confederacy of Dunces 5 mentions
14 Do Androids Dream of Electric Sheep? 5 mentions
14 The Great Gatsby 5 mentions
14 House of Leaves 5 mentions
14 A Song of Ice and Fire 5 mentions
14 Ulysses 5 mentions
14 A Wrinkle in Time 5 mentions

Yes, The Hitchhiker’s Guide to the Galaxy on its own got the same amount of votes as the entire series on its own.