What phone should i get?

my mom said in August, she was supposed to get an upgrade to a new phone, but, she said that she will keep her phone, and let me get a new one! now, we have sprint. so it has to be a sprint phone, it can't cost any money, i mean the phone is free, we have to pay for a plan though, so does anyone know which would be a good sprint phone for free? i would like it to be a messenger phone. thanks!