So heres the deal, I only have enough money to get one lens, and the Sigma is about as much money as I can afford. Currently I have two really cheap Sigmas that im not even sure are worth the plastic they're made of. One claims to be a 28-80mm f/3.5-5.6 II and the other is a 100-300 f/4.5-6.7 DL. They were given to me as a gift with a film body and i've recently purchased an XT so im getting rid of the film body. So judging by the two lenses I have, which lens do you think would be the best choice? Thanks!