What's best iPhone deal for NEW customers, any carrier, need to buy 3 phones/lines?

I am in the midst of a divorce and need to move from Sprint and need 3 new phones and 3 lines for myself and my two children (ages 17 and 21). Would like IPhone 11s or above. ..OK with a contract, but want to find the best deal on the phones and on the monthly service. We have trade-ins eligible for most of the trade-in deals, but I am overwhelmed trying to compare all the deals, and am not up to the complicated deals I see some of you craft (buy a phone here, trade-in at higher value there, leave after a month, etc.) My kids will both will be in college next year so pretty high data usage, etc. Any recommendations as to what carrier offers the best overall deal? I'm also 56, so qualify for most plans for, I hate to say it, seniors, and am a government employee so qualify for those who offer government discounts.