Aside from the lower price, the Westslope seems quite a bit lighter than the Monorail, so it's easier to take it on and off the car, which I'm doing more frequently now given what happened to the previous rack. The Westslope also has better ground clearance, which was important for me because I'm driving a sedan. The Monorail would always scrape going up my steep driveway (even after I cut off a little extension piece that didn't appear to have any structural purpose). In contrast, I haven't scraped with the Westslope yet on that same driveway. I also like how the ratcheting arm works a little better on the Westslope. Not only does the mechanism not hang up like the Monorail sometimes did, but there is a molded in flat spot that allows me to push down more easily to get that one last click from the ratchet. In terms of holding my bike securely (a 29er with just under a 27" wheelbase), both racks seem equivalent to me.