If you are looking to get away from a canister, there are a couple options.
1. HOB filters. I am personally a fan of the Aqua Clear filters when it comes to HOB's. They are relatively inexpensive and many have even converted them into refugiums.
2. HOB overflow. With you having a non drilled tank, you could look at a hang on back overflow if you were interested in setting up a sump. While they are not the most ideal, plenty of people have used these and had successful tanks.
Is your long term plan to keep the tank a FOWLR or are you planning on adding corals at some point?
IMO if you are looking for a different filtration setup, I would keep the canister hooked up and running while you get your game plan together. Adding a sump does not require drilling your tank, but it will require a bit more thought as you look at return pumps, skimmers and filter socks/ fleece rollers.
