Geometric topology is more motivated by objects it wants to prove theorems about. Geometric topology is very much motivated by low-dimensional phenomena -- and the very notion of low-dimensional phenomena being special is due to the existence of a big tool called the Whitney Trick, which allows one to readily convert certain problems in manifold theory into (sometimes quite complicated) algebraic problems. The thing is the Whitney trick fails in dimensions 4 and lower.
As to my background, I've learnt Boothby's book "An Introduction to Differential Manifolds ...". I recently want to dive in some depth into Geometric Topology. But I found the literature is quite a mess. Could anyone suggest a textbook or at least a sequence of books and papers that leads to the frontier of this field?
Stillwell's book Classical Topology and Combinatorial Group Theory is a good first place to start to get a feel for the techniques of geometric topology. If you want to get your feet wet in the world of $4$-manifolds, there's a great book called The Wild World of $4$-manifolds by Scorpan which could serve as a source of further papers for you to look at. For $3$ dimensions, I would start to learn some knot theory. There are many good books on this.
In general, you will still need to know algebraic topology, even if you are only interested in the geometric side of things. In my opinion, Hatcher's book Algebraic Topology does a superb job explaining the subject while maintaining geometric intuition.