I realise this is a popular genre and encompasses many different things from Game of Thrones (which I have not read yet, but have the first one) to historical fiction which plays with history, or imagines different history. I first tried it (well I read LOTR when I was about 15, but who didn't?) with that Thomas Covenant stuff when I was at uni in the early 80s, but could not get on with it. I went off sci fi, because it is too much of a cheat with time machines, warp drive, and all the other stuff. I ended up with historical fiction (like Romans, Medieval war stuff, Bernard Cornwell (who is a bit variable), some Viking stuff which varies as some is just about battles and stuff, but some has Norse gods popping up magicking. There are magic swords, dragons, witches and warloks, sorcerors. A lot of "fantasy books" seem to be incredibly long like GoT, but are they too much? By page 400 have you lost the plot? What do readers prefer?