Well, you ask a broad question, you get a spectrum of answers ! This is of course one of today’s though questions. Some elements to consider :

1. How long will the cabling be used ? If you plan to leave the building in 3 years, your decision may be different than when you plan to stay long term.

2. What will the cabling be used for ? For data, I reckon that Ethernet at all speeds (10/100/1000 Mbps) must be supported, hence UTP Cat5E is the minimum. If you use the same type of cable for telephony (gives you more flexibility) any extra cost for shielding weighs in more heavily than when it is data-only.

3. While fiber cabling by itself may have comparable price, in practice I don’t think that fiber-ONLY is an option. Hence your choice is either copper or copper + fiber. The reason of course is that there are very few fiber-based telephones, fax machines, etc. on the market. Also, you will find that fiber-only limits your possibilities and raises cost in other devices, e.g. PC’s with built-in Ethernet, ditto printers, etc.

4. Shielding (STP or FTP) can help, but has its own risks and expense. My rule is : use shielding only if there is a demonstrated necessity, e.g. high level of EM noise. The ’if it doesn’t help, it can’t hurt’ approach is not applicable. Any fault in your shield brings your cable down from better-than-UTP to worse-than-UTP. Hence I don’t think that paying the extra x% for FTP buys you real peace of mind. Unless, of course, UTP will not work in your particular environment. Given that it does in the vast majority of office buildings, your FTP proponent should come up with concrete evidence, naming the sources of radiation or showing the measurements.