It would be all looks the weight difference can't be that signifigent, and considering what they are would not be a factor. The aluminums would not rust, and look better longer. The cheapest would be good enough.....I think. I have read many times that they do make a difference and many people say that. I have read up to 15hp but that is likely on a hopped up engine not a stock one. The downside is if you do not have a 3G alt, and have AC, power options, big amp etc it may cause problems at idle for sure. You can leave the alt pulley stock to help this, but that is taking away some of the advantage of the other pullies. If your car does not have a lot of these options......get them!!!!! My car came with smaller pullies so I cannot compare and I have no power options so I have no problems with the alt, plus I hand polished my alt, so I ain't buying another one.