My experience generally is that you get what you pay for. Verizon and AT&T have the best service and best coverage generally, but are more expensive than Sprint or T-Mobile.

Do you own phones or are you going to be acquiring new ones? If you own phones, Straight Talk is cheap and gives you access to AT&T's network at a lower cost.

I personally have Verizon because they have the best coverage work well at my house. I prefer to pay a little more and have better access when I travel to rural areas.

If cost was the only consideration and I needed to include a phone, I'd probably go with T-mobile. Free streaming of many services would help a lot with data, but their coverage outside of metro areas isn't as good.