JBL had one of the longest runs in recent WWE history. Point is though, there have been more heel champs in recent times than faces!
And to be honest, a long run in the last 20 or years or so, has been no more than a few months or so, not like the old days when a title run would be a year or more!
Austin (heel) held a belt for 5 months, Randy Orton held a belt for 6 months & JBL held a belt for 8 months. Those have been the longest other than HHH, in recent years! In current WWE climate, these actually classify as long runs!