To be frank - the current NPCs don't vary enough. They did at one stage - for around a week - then they got nerfed as it wasn't possible for every human to be master of the universe and gamers are just used to being "The one true hero" - however ridiculous that might be in an online game.
Personally? - I like the idea of looking at an NPC and thinking "no ' chance" and chuckering off before I got killed. I looked at FDLs from my Cobra and just knew it wasn't worth the risk. I looked at Eagles and thought "what rank are they? - is it worth a go?" - I enjoyed this aspect of the game immensely. It was a whole new challenge.
Now. They're rubbish, mostly.
The other day I look on a dread pirate lord in the Cobra. He's in a Vulture - and it was easy. He just stopped flying a couple of times and just hung there whilst I shot at him - and he's supposed to be a master pilot. Now my Cobra IS a little engineered and ought to at least have a chance against someone in a Vulture, but it shouldn't be *easy*.
For me, an Elite NPC ought to put up a damned good fight in whatever they're flying and be virtually unbeatable unless you really know what you're doing if they're in a better ship than yours.
I took on an Elite pirate lord mission the other day, in my multipurpose Python (not dedicated combat, no armour).
I went in expecting a decent fight. Double checked my systems and firegroups, and dropped in to the USS.
1 Elite Anaconda. Nothing else.
1 minute later I was heading home slightly richer.
Not what I was expecting from an Elite mission NPC.