I have an IPhone 6 with ATT Next. I'm eligible soon for an upgrade. Just bought my wife a 6s plus. But I paid for it all up front so she has her own plan and there's no contract. Just month to month. I want to get the 6s plus too I think now because I like it so much and isn't as awkward to carry in pants as I thought it would be. Does Next make sense? I pretty much get every model of phone. Sometimes I skip the S. Or, can I pay the 150 bucks I have left to become upgrade eligible, trade in my 6, and then buy another 6s plus straight up and continue with no contract and a lower monthly cost? What makes more sense? I have a grandfathered unlimited plan if that makes any difference.