Lantus is a long acting (24 hr) that generally has a flat profile. NPH is an intermediate acting insulin (lasting 6-8 hrs) that peaks in action at about 4 hrs.
Lantus is overall a much better choice for basal coverage as it's more steadily absorbed (NPH is very variable based on injection site and activity) and the peak can be a killer. Ideally on Lantus, one should be able to skip meals and not go low.
The best insulin plan short of a pump is Lantus or Levemir once or twice a day with coverage for meals based on bg and carb intake with Apidra, Humalog, or Novolog. However, this means an injection of Lantus once or twice daily, plus a injection every time food is eaten and when bg is high. This often meals 4+ shots a day, and some people aren't willing to do that.
Enter in NPH. Notice that nice spike NPH has? If injected in the morning, that spike can be used to cover lunch. It's much hard to work than a fast acting insulin, as activity and carb intake need to be consistent, and it can't be used to cover an already high bg, but it can save someone a shot.
Also, some people have Dawn Phenomenon, and if injected at bedtime, NPH's peak can cover the 3am spike some people tend to have.
So in short, it has it's purpose. It may be used in conjunction with Lantus if the person overall needs more insulin coverage than their NPH dose can provide without the peak causing lows.
NPH and Lantus can work, but it takes careful bg analysis and trial an error. It's not going to be a good regimen for most people. From the sounds of it, between the quite bad a1c you quote (8.6 is very out of control, not a little) and the fact that it sounds like you have many patients on it, I'm guessing your prescribers just don't know how to use insulin well (a common problem).