Pullets = all female chicks although sexing is never fully accurate so there might be a rooster or two. Straight run = a mix of hens and roosters. If you buy pullets you should get 95% females and with straight run you should get aroud 50% females. I recoomend buying pullets if you plan on raising them for eggs. The straight run is cheaper initially but ends up being more expensive.
id go with the pullets.b/c if you go straight run youd get atlest 50% roosters or more.an unless you want to eat them.you wouldnt be getting your moneys worth from straight run chicks.