Corruption all the way for me. Just something about bringing out the inner deviant in a lot of the more timid characters that really appeals to me. I think Blackheart games has a good one called The Assistant or something like that in my opinion is one of the better ones. I haven't played it in a while though. Guess I'm going to go see if I can find it now.
Sounds bad, but grooming is probably the best game element because it [supposed to] requires strategy. Romance is either yeah or nay while corruption implys lies & blatant coercion. Grooming is subtle and is supposed to create the illusion that they came to the decision themselves. So, romance+grooming is probably a better reward system. For a simple VN then it really doesn't matter imo.
Usually for me I like to try out all routes but the first I almost always go for is the corruption path (or dark path if there is one). Mainly just because it's fun to see how deviant the dev is and how far one can take things.