I do both for my grows. I top twice usually, depending on strain, and then lst. I use twine and clothes pins to lst. I also make sure I lst before the plants go into the flower room as they are more supple, if left too late the branches are too hard and can break easily. I begin by bending a little and then over the course of a week or two increase the tightness on the twine until the center of the plant is opened up somewhat. I like this because I get bigger buds, and can look into more of the plant to check for pests, mildew, etc. My plants usually resemble 2-4 foot bushes. Don't over do it though because too much lst and topping can be a pain to keep the branches from breaking under the weight of the buds, though I've had worse problems! haha

For the vote...I would go with topping. The reason is that I feel that I have to top my plants, but lsting a plant is just a bonus! Really, I would like to vote for both...