For a legislature one could use also multi-winner and proportional methods, but I think the question was what single-winner method to recommend. (I'd probably recommend proportional methods for most multi-winner elections, unless the community explicitly wants to have a two-party system.)
Jameson Quinn mentioned the "kingmakers". Delegating the power to decide who will win to one or few candidates is risky since (depending on the environment) that might lead to buying personal benefits, instead of basing the decision on one's sincere opinions or doing only political trading. Kristofer Musterhjelm mentioned the possibility that the limitations of current voting machines might limit the maximum number of candidates to rank. Good sigle-winner methods tend to require evaluation and some knowledge of at least all the major candidates. Maybe ranking is not much more difficult than other simpler approaches like approval. Different ballot types might be used, depending on the preferences of the community. If the complexity of allocating some preference strength (e.g. a rating) to at least all major candidates is not too much, (almost) any Condorcet method would be a good first guess. (Alternatively also Range could be used for clearly non-competitive (and non-majority-based) polls / elections. But probably the question addressed competitive political elections only.) To pick one of the Condorcet methods one might use criteria related to simplicity, performance with sincere votes, performance with strategic votes (hopefully an maybe likely strategies will be marginal in Condorcet), ability to explain and visualize the results, easy marketing. All Condorcet methods tend to give the same winner in almost all real-life elections since in most cases there is a Condorcet winner, and even if not, the winner still tends to be the same, and even if it was not, then it will be difficult to say which one of the about equal candidates should really have won. Matt Welland discussed the Approval strategies. The strategy of approving some of the frontrunners and not approving some of them is well known. Therefore it makes sometimes sense to distribute fake (or hand picked) polls. One may also distribute different polls or other messages to different target audiences. I wrote something about this few years ago. See http://lists.electorama.com/htdig.cgi/election-methods-electorama.com/2006-December/019127.html. Juho
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