Quicktrip is good b/c I believe it will patch together multi-airline itineraries--so it shows wayyyyy more options for a 2-leg commuter going through a hub served by multiple carriers (for example, ORD)

That's the only flaw with passrider that I wish they'd fix--it only builds codeshare/same-airline itineraries

Not to dog on any of these sites though--it seems like passrider in particular is a labor of love that doesn't really generate much--if any--money for whoever built it, even though it's prob the most widely-used site for tons of commuters