I love the new digital medium topcoat...it's got the UV protection that most works really need. What I'll say about using an acrylic medium as a top coat is this: in certain climates, you'll find it stays sticky. It's not a good idea for finishing a page in an altered book, for example, unless you're going to then coat it with a spray, cornstarch, or wax. Oh, there's another possibility...Dorland's Wax is loved by many. Just to give you even more confusing possibilities
I don't think there's just one answer here. It tends to get down to what you like.