This is purely a matter of opinion, of course, but anyone who says it's something other than The Lord of the Rings is going to have to justify that claim.
LotR is epic High Fantasy. If you like Low Fantasy, or prefer something darker, some suggestions (a warning first that some of these are quite dark, and some are quite graphic):
the alcymist
The Bible.
In my opinion Deltora Quest.
Harry Potter and the Sorcerer's Stone
a book with fantasy and imagination
it is a fantasy book
The Book of Fantasy was created in 1940.
Yes- to consider a book a fantasy book it must have a story that has fantasy elements in it.
Comic book stores are your best bet.
The ISBN of The Book of Fantasy is 0-670-82393-7.
You might check EXPOSE or EXOTIQUE book collections. There are also many other books covering fantasy art (used in fantasy movies, fantasy book illustrations, fantasy games..)
Lord of the Rings is hands-down the best fantasy series.