Education for the next step up???

I am planning on starting my master’s work soon, but I am undecided as to which way to go, a technology-based MBA or a MS in CIS. Does anybody have any feelings what would prepare me better for the future (more of a managerial role)? I was initially set on the MS in CIS, but have been doubting this recently. I currently do a job that entails web development, proj. mgmt., and some business analysis. Thanks.