I think we should use both, except the actual top-list should provide incentives. We should also maybe limit the amount of characters like most top-list's do instead of it being a post it could be a short description. Also, by having an actual forum post advertisement it allows owner's to give out content updates every week and hear feedback without a review that is permanent.
Side note: I love the review system on the top-list although, I think that we need a better way to actually vet the reviews given. For example, you can only post a review if you actually hopped on that server and maybe it will calculate how long the person has actually been on the server for. Without this way people who have never even played the server can bash the server for no reason. I've seen happen in other communities. If there was a way we require servers to be linked via forums somehow ( I would have to look into this more) it would be great. We can make it so that the person has to have played the server for 30 mins in order to leave a review or something.
There would have to have extensive work to be done in this case but again it's just an idea. Never hurts to look into it, if it's too complicated then we can find an alternative.