I like reading books with a long series.
I am currently working on:
Redwall (on book # 4 Mossflower)
Eagle Series (on book # 9 The Gladiator)
Jack Aubrey (stalled at book # 4 The Mauritius Command)
I have also enjoyed the following in the past:
Forgotten Realms (D&D)
Song of Fire and Ice
I also read lots of military history with an emphasis on the Napoleonic period and World War Two.