I own a 18-55 IS and for the price I think this lens is a good lens. The additional benefit of owning this lens is that it is light and compact. So, if you like to travel light this lens is a plus. On the other hand, I also own a 70-200 f/2.8L. This lens is also a fantastic lens. However, your question is concerning the 70-200 f/4 No-IS. My view in this regard is that if you pick the 70-200 No-IS you will be getting a phenomenal lens. No question about it. So, if you can live without IS, go for it. Finally, keep in mind the 55-250 is a very good lens for the price. It also has IS, is light and it has more range.
Hence, if I were you I pick the Sigma 17-70 and the 70-200 f/4.