Zong isn't bad for internet - but they have pockets where signals aren't of good quality. It's the same issue with Telenor as well. Maybe Warid doesn't have these issues because when they were deploying 4G, they didn't have a fallback network (Zong had 3G), so they made sure their 4G network had to have good coverage (I know the church in Saddar, Rawalpindi - opposite CSD - didn't get good signals when I went there once to attend a wedding).
Sometimes, I really wish these operators would actually listen to their consumers and set up additional cells (not towers - just cells. Even femtocells!) instead of spending so much on marketing.
Telenor already has a lot of cells, but why their signals are crap, beats me. It's funny, in between, at Green Valley, I wasn't connected to a femtocell (I know because I was playing around, and my phone connected to a cell which was far away, since the signal strength fell to -95dBm) but the SNR was alright-ish (hovering between 8 and 12ish), and I managed to get a downstream of 320KB/s (approx) on 3G.
I can never get that at home, or at work, with similar signal levels. And since I was inside, I don't know how the line of sight theory would work (since signal strength was weak).