I suspect that they might be a little bit "of their time", but I adored P C Wren's Beau Geste trilogy, which I must have read when I was about 13 (1970s). In my 20s (1980s) Anthony Burgess's Earthly Powers scooped the favourite book prize (with one of the most striking opening sentences I've come across!), until knocked off its perch a few years ago by Wilkie Collins's Moonstone, which I see has already had a nomination here. In turns gripping detective yarn, social commentary poking fun at the pompous and powerful, and laugh out loud comedy.
In passing, and I mention it only because we are talking books and I have just read it, I found Hemingway's For Whom The Bell Tolls interesting, not only because it is a very fine piece of work and illuminating of the Spanish Civil war, but also because it turns out to be the provenance of the comedic "did the earth move for you" trope, which was part of a rather serious (well the whole book is) passage describing an amorous engagement between the protagonist Robert Jordan and his paramour Maria. Who knew!?