Currently, the most promising AR antagonist is in stage 3 trials: MDV3100. Unlike bicalutamide, it prevents the nuclear localization of the AR, as well as promotes its degradation, rather than purely binding it competitively. This drug is by far the most promising in terms of treatment of prostate cancer and male pattern baldness (as well as other androgen mediated diseases). This is actually the drug that RU58841 most resembles. Although RU is a seemingly cruder analogue of MDV3100, it might be safe to assume that the two have similar properties due to structural similarities. So if MDV3100 was available, it would seem to be absolutely the best investment, but as long as its still in development, RU58841 (perhaps combined with fluridil to moderate some of the potential toxic effects of RU) SEEMS to be the most viable alternative.
http://www.medivation.com/product-pipeline/mdv3100
http://www.medivation.com/product-pipeline/mdv3100