Whats the best tmobile at@t verizon and sprint?

i want a cool phone with unlimed texing. i would like it to be all under 50 a month. i need little calling like 50-100 cause i dont talk like at all...so ya. also if this is not posible what prepaid plans by the month are the best.i saw at@t had cool phones but its 2 dollars a day thats 60 a month and for prepaid thats a little steap i think. thanks!