7870 XT. There is no real discernible difference between both the 7950 and the 7870 LE. The 7870 XT isn't a regular 7870, it actually has the GPU from the 7950 implanted onto basically a modified 7870 PCB (Meaning it has 2GB vram and 256 memory interface). If you're gaming at 1080p the 2GB doesn't even matter, and it has been shown in reviews that the 7870 LE is most of the time 1-2 frames slower, which can easily be made up with overclocking.
Not to mention, the 7870 LE has a better cooler than the 7950 you suggested, which has a reference cooler. Have you seen the reference 7950 cooler? Damn that thing is LOUD.http://www.tomshardware.com/reviews/radeon-hd-7950-review-benchmark,3207-12.html
Also, probably the reason you found different wattage uses, is because some websites have different rigs (Some people use hugely expensive i7 3970x, while some other websites use things like i5 3570k's), and because people measure them differently. Some websites measure only the GPU wattage, while others measure total system wattage.