My suggestion!

Personally, I'd register as recreation. Flight rules are much less stringent for non-commercial work. I can think of no advantage of commercial aircraft registration. Perhaps I'm overlooking something though. I am aware that a couple of years ago there were suggestions that taking photos of your own farm for potential financial decsions would throw you into a commercial category. I have heard of no one being hassled for doing that. But, if what you do attracts a lot of attention, then you may have to answer questions. By that I mean flying over a football stadium filled with people. But, flying over a washout in the back 40 to decide if it needs fixing? No one cares.

Works the same with full size aircraft also. 

Now, if you want to get a commercial drone license & fly for pay, go for it. Costs extra money too for that license.