Judging by the painted trailer I'm guessing you're in fresh water, it looks like you have a five bolt flange which means you can use 12" brakes that will give you good stopping power with a 19' boat. If your tow vehicle has a brake controller electric brakes might be an option but they are still going to be drum brakes which some people don't like for maintenance vs discs. You can find galvanized electric drum brakes if you look around.
I added surge drums to my trailer close to 20 years ago, they usually last approx 6 seasons then I might have to change the wheel cylinder (inexpensive, though compared to a brake caliper on a disc brake). At the time disc systems weren't that good, so it was a toss up between disc vs drum. Now, just about everyone would say go with surge discs.