I have been reading books since I ... uhm ... since I started to read XD. I have a lot of favs :-
1. The Hardy Boys
More These stories feature dynamic detective duo and brothers Frank and Joe Hardy who solve baffling mysteries. There are lots of series under this category targeted for school-going people as well as college students. According to reviews, even adults find them interesting.
2. Nancy Drew
More These stories feature a girl detective Nancy Drew who solves baffling mysteries with the help of her two friends. Nancy Drew has been created by the same guys who have created The Hardy Boys so the stories are of a similar genre. But in Nancy Drew, fight scenes are excluded unlike The Hardy Boys. Also the books are more romantic than The Hardy Boys.
3. The Three Investigators
More These stories feature three boys Jupe, Pete and Bob who solve the mos baffling mysteries ever. Their mysteries are more mysterious than those of either The Hardy Boys or Nancy Drew. The books do not feature much violence or romance but compensate it by baffling Sherlock Holmes style mysteries.
4. Doctor Who
More This series is an entirely different one from the one mentioned above. It is a Sci-Fi story based on the adventures of the Mysterious Dr. Who and his time travelling machine, the TARDIS. The books are totally awesome! The original books were written based on the TV series of Doctor Who. These books are meant for readers of all types.
5. The Executioner aka Mack Bolan
More This is a highly explosive, violent series featuring One-Man Army Mack Bolan aka The Executioner and his war against organized crime. These books simply rock! They are based on reality. The books contain war, violence and extreme gore. Also there are tremendous amount of books to last one a lifetime! There are also a lot of spin-off series based upon The Executioner which are as good as the original series.