I just signed on to ask the same question. I have been researching and I am going between the Sole F63 (or F60) and the Proform 995 (or 600). All of which got decent reviews from Consumer Reports.
Today I bought the NordicTrack T5.7. I am getting it delivered next week. I was able to try out both the Soles and 2 Nordic Tracks.
I didn't like the Soles because they took a while to get up to the desired speed, the control panel was too low (short) and I am 5'3" (it felt ergonomically awkward) I didn't like the display (it was hard to read- small and blue), and I didn't like the speed controls (if you wanted to go faster than 6 miles/hr, you had to increase your speed by .10 of a mile/hr. It was annoying since I usually run between 7 - 8 mph.
Both the Soles and the Nordic Tracks felt very similiar when I ran on them. I couldn't really tell a difference.
Other than a $200 price difference, I didn't notice a difference between the The NordicTrack T5.7 and the T.7.0. Both were very smooth and stable machines. Both had a button to increase your speed by 1 mile at a time (button for 7 mph, button for 8 mph and then up and down arrows to adjust by .10s). The sales lady at Sears told me that the 7 had a bit more cushioning, but I couldn't tell.
The 5.7 is on sale at Sears.com until tomorrow, I think for 539. The lady at the store was able to match the price and waived all but $20 of the shipping/set up fee. I also got the 3 year warrently. So, with all of that plus tax, my total came to $777.