The Ride 7's are awesome, but I would definitely go with the Pegasus 31's, especially based on price/performance ratio.
The Ride 7's are some of the best reviewed neutral trainers you can buy. Just look at the aggegated reviews here:
http://www.tackl.com/gear/ride-7-running-shoe-24935
That said, they are not that much better than the Pegasus 31 to justify buying them over the Pegasus 31's or even the Ghost 6's (which i bought heavily discounted a few months ago, and love). My wife owns both and she actually prefers the Pegasus 31. The Pegasus are better looking. The Ride 7's definitely have more "tech" built into them. I own both Pegasus 31 and Ghost 6, and it's quite honestly a draw. I rotate between them to keep my feet in shape.
Considering the $110 price tag for the Ride 7's and the fact that Pegasus 31's are now selling for as low as $65-75 since they've been out longer, I'd definitely go with the Pegasus 31's.