carriers because I wasn't too thrilled with network coverage, speeds, occasional dropped calls, etc.

I did some comparison shopping for a 4 smartphone plan across the major carriers and found the following:
- Sprint and T-Mobile are pretty comparably priced and are the cheapest
- AT&T would have been about $40/month more
- Verizon would have been about $80/month more

There were some minor differences between the plans (amount of data, etc), but I tried to price as close as I could. My Sprint plan is an Everything Share plan with unlimited data, and nobody else has a reasonably priced unlimited data plan. But between the 4 smartphones, we usually don't go over 7 or 8 GB in any given month, so I don't necessarily need unlimited data.

In the end I decided staying with Sprint. Reviews show that people are just as disappointed with T-Mobile coverage here in Texas, so it didn't make sense to change there. I could have got faster speeds and better coverage with AT&T or Verizon, but in the end it just wasn't worth the $500 - $1000/year added cost to switch to them. The network issues that I have had are an inconvenience, but in the end I'd rather have $500 in my pocket every year if it means getting 15Mbps LTE speeds rather than 30Mbps.