There are a few series I’ve read in their entirety multiple times:
The beast must die
No. 6
Nabari no ou
Fruits basket Another
Sweet pain
Others I’ve not reread in their entirety but go back to revisit often:
Hello veterinarian!
Kim Ohjin’s adventures with strange animals
Natsume’s book of friends
Limited run
Mobius strip
Passion
Oji...... reply