Just checking the active roster, not counting NXT title wins in the mix, the ranking for people yet to win a title would be:
1- Rosa Mendes (debuted early 2009)
2- TIE: Darren Young/Ryback (both debuted in NXT season 1)
3- Tamina Snuka (debuted May 2010)
4- TIE: Alex Riley/Bray Wyatt/Titus O'Neil (all debuted in NXT Season 2)
5- Naomi (debuted NXT season 3)
6- Byron Saxton/Konnor/Fandango* (debuted NXT Season 4)
7- Sin Cara II (debuted summer 2011)
8- Cameron (debuted January 2012)
9- Summer Rae (debuted May 2013)
10- Erick Rowan (debuted early July 2013)
11- Eva Marie (debuted late July 2013)
12- El Torito (debuted September 2013)
13- Xavier Woods (debuted November 2013)
14- Emma (debuted February 2014)
15- Bo Dallas/Adam Rose (debuted April 2014)
16- Viktor (debuted January 2015)
17- Kalisto/Neville (debuted March 2015.)
*-Fandango did not win a title, but did win the non-title honor of being NXT Season 4 winner.