First thing to consider. We never buy phones from carriers. We buy unlocked phones direct from the manufactuer or used from Swappa.
Second, do not develope brand loyalty for carriers. Connectivity is closer than ever to being a commodity. Buy the cheapest carrier and plan that meets your needs. With unlocked phones you can switch carriers with ease to take advantage of better coverage, better pricing, or added plan features. Your life will not be static nor anchored to one locale. Your choice of phone service should adapt to life's changes.
Next, group plans will almost always be cheaper than individual plans. Prepaid plans will almost always be cheaper than postpaid plans. For similar service.
Lastly, you can get phone seevice practically free, or you can pay big bucks for premium devices on post paid unlimited data plans. It will be up to you to detemine where you want to fit in the price ladder. Here are some things to look at:
Free - Google Voice on WiFi only
Free with moderate taxes only - Sprint one year free (if you pass the credit check)
In cost rank order:
Google Voice on WiFi and a limited data only plan (FreedomPop)
TracPhone yearly plan from eBay
Prepaid limited data plan (do a Google search of "MVNO")
Prepaid unlimited data plan (same players)
Post paid limited data plan (Sprint, T-Mobile, AT&T, Verizon)
Post paid unlimited data plan (same players)
Since you asked, I am on an 8 member post paid Military One unlimited plan at T-Mobile. We pay $20 each per month, taxes included. If someone in your family is active duty or a veteran, they should check it out. Maybe you could tag along. :)