See if you dont prefer amd, then you are stuck with i5 7600 because although coffeelake chips are gonna launch this october and are better investment than 7th gen but the motherboards thats gonna be released alongside are z370 motherboards only which will be quite expensive. So, if you are looking for a budget build and want a coffeelake cpu, then you will have to wait till november end or december when maybe the h370 or b350 mobos are gonna launch but again the release dates for these mobos aren't out yet and those are speculations.
the i5 7600 wont be a bad investment if you are only looking at intel products and want a pc right now.