at the cost of not exceeding other requirements by as much as the YF-22. Namely, the YF-23 was faster and stealthier, but the YF-22 still met the minimums of the USAF's RFP, while being more maneuvable, and carrying 1/3 more missiles internally.

Not to mention that although the large "tailerons", helped make the YF-23 extremely maneuverable, the vectored thrust on the YF-22, was a step better - particularly at high AoA/low speed. Now, was it that much better? In reality it wasn't a ton better, probably almost a wash, but you always have to remember that the time period of the competition played a role in the selection of the winner.

At the time, we were seeing Russian Su-27s doing these ridiculous high AoA/low speed maneuvers (like the Cobra) thanks to thrust vectoring. So, at the time of the competition, that small difference in maneuverability was seen as a much bigger selling point for the YF-22, than say the YF-23's small advantage in supercruise speed or stealth. 

The electronics suite and cockpit on the YF-22 was also well ahead of the YF-23. Not sure if it was lack of funds, or what, but Northrop basically installed a similar cockpit to the F-15E in the YF-23 (a trick that Lockheed actually used with the F-117). However, showing up to the competition with a Gen 4 cockpit in a Gen 5 fighter, wasn't the best move. Especially when the YF-22's cockpit had a Star Wars feel to it at the time. It called into question whether Northrop had the resources to take the fighter into full-rate production without encountering enormous cost overruns. That was hugely important, because when the F-22 was ordered, the USAF wanted at least 750 of them to replace the entire F-15A/C fleet as the nation's primary air superiority fighter. Unfortunately, thanks to idiots like Dick Cheney (among other things), we ended up with less than 200 examples.

That said, the YF-23 may be among the best fighters never built, and certainly one of the best looking.