As for faster data, I'd like to see the actual speed tests for that, and for the signal strengths overall it really depends on area. In my area, sprint has little coverage - I can be in the same house with a sprint person and I have a great signal and they have little.
But for the prices - I'm not sure what plan you had, but I have 1400 min, 5 lines, unlim text on all and data on one and pay $200/mo. If I just had 2, both with data, it'd be the same price (drop 3 lines - $30/mo, add data - $30/mo