Cricket and Sprint network speed is about the same with the advantage to Cricket in most areas/days.Cricket was bought by ATT last year and as such run on the same towers as ATT, so coverage should be better than Sprint. However data speeds and call quality from what i can gather isn't nowhere near as good as ATT so therefore Sprint has them beat in that department. I think Cricket wins affordability too so to sum it all up on Cricket you'll have a phone that'll work poorly in a lot of places for cheap.
Sprint is garbage man, I tried sticking it out with them while they improved their network and its beyond terrible. It is not worth the headache with those guys IMO.