I would pick the Astro over the "brand X". At least I have heard of Astro and actually own some of their tools and they are of "reasonable" quality.
Like others I rented the tool for a long time but got tied of the generally poor condition of the rental tools so I bought my own Harbor Freight version. I have used to to replace front ball joints on a Mustang and it does work.
Remember to lubricate the threads before use. The tool will live longer if impact tools are not used (hand tools). Remember to eat your Wheaties.