I always liked Terrance Nunn - his reputation took a dive after the Texas fumble, but he had overall one of the best careers of any receiver at NU. Didn't he start as a freshman? He had a great game in the Alamo Bowl to help beat Michigan and was solid throughout his career. He faded some during his senior year but overall (except for that one fumble) was a bright spot during a dark time. I wouldn't necessarily put him near the top of the list, and I even think all of our current starters are better than Nunn, but I was always a big fan.
Nunn was overshadowed in his last year or two by Mo Purify, who I think was one of the most talented receivers we ever had. It's too bad Purify only really had a year and a half to play, and he was under-utilized. He seemed to be able to make insane grabs when the ball was not on target. In the 2007 Kansas game, which was a horrible debacle, one of the few bright spots was Purify having a really good game against Aqib Taalib, who was regarded as one of the best CBs in college football that year.
Kenny Bell has that same kind of ability as Purify to find the ball, with more speed, and four years to showcase it, which is really exciting.
Also, I lol'd at seeing Frantz Hardy's name anywhere close to a best-of list. Niles Paul had some good talent and flashes of brilliance, but way too many drops and mistakes (I think Paul's drops made us forget how many Hardy had). Paul had some clutch plays that won us a couple games, but some really bad performances that lost us a few. Never lived up to the hype.