What to consider when chosing a UTP CAT6 brand

You want to use Category 6 or 6a (aka "Class Ea"), as this will allow use of 10 GigE over copper if you ever need it:

http://en.wikipedia.org/wiki/10_Gigabit_Ethernet#10GBASE-T

Cat6 allows for 37-55m (121-180 ft) cable runs (depending on how much electrical noise there is in the environment) for 10 GigE; Cat6A allows for 100m (330 ft) runs at 10 GigE. Either will be fine for 1 GigE. If your runs are with-in the shorter lengths, then Cat6 should be sufficient. Don't think UTP or STP would make much of a difference.

I'd get quotes for 'parts and labor' for each type of cabling and see what the cost differences are: it's usually easier to "future proof" things at the beginning than retrofitting things down the road.

If you're doing any fibre you may also want to look at the costs for both OM3 and OM4 (which was just released and will help with future 40 and 100 GigE support in your DC).

I would advise against using unshielded CAT6. So, not UTP cable.

It's more expensive, but a cabling project is not really something to cheap out on, because it's difficult to troubleshoot when your problem is interference in the wire, and if you do have to replace the cabling, it's usually a huge pain (and expensive to boot). As you say, at least some of your cables will run close to 220 volt power cables, which offers the possibility of noticeable performance degradation on unshielded cables.

Better to do it right the first time so you don't have to worry about doing it again.

Regarding STP or FTP, I'm not sure if there's a functional difference between the two - FTP shields the whole cable, STP shields each pair, so in both cases, the wires carrying your data are shielded. Given that I'm not sure there's a meaningful difference between the two for practical purposes, in choosing between the two I'd decide on price or brand, and go with the cheaper price or the brand I like better.