I've used both and I truly don't have much of a preference either way. I tend to use alot of resources running After Effects and Premiere, so I have had the enjoyment of crashing those programs on both a mac and a windows machines!
I think macs have some of the best monitors I have seen, but they can be a bit pricey. If you are editing on a portable, you may want to consider having a docking station with an additional monitor. Editing with 2 monitors when you can saves so much time and really gives you a bigger area to see everything at a glance.
So, my advice is to get whichever makes you feel more comfortable, but don't get swayed by people who state that you must run a mac to do decent video editing. It simply isn't true. But, if you prefer final cut, or the apple interface/hardware support, that might be a good direction to go.
