After a post in another thread I felt like making a true tribute thread with all the reasons:
Neocron still doesn't hold your hand, you have to earn everything and you're expected to be able to read a manual and figure things out for yourself without a 90-part tutorial.
Neocron has a POINT to exploration and doesn't lay everything out on a platter for you, you have to explore and master the game world if you want the best of everything.
It's possible to be anything from pure PvE to pure PvP to total pacifist, though skill points might not come easily for all paths all can be viable.
You aren't locked into a set build that defines what you MUST be. You have total freedom to pick your own path according to what you enjoy. Even if it's totally gimped you can try it. You could be a droner tank or a H-C spy or anything in between.
The only MMO ever made that mates vehicle combat to ground combat in a realistic way.
The BEST animations and sound design of any MMO. Sci/fi weapons FEEL sci/fi. You're loading hydrogen gas, charging capacitors, stabbing in quantum matter canisters. Not every gun loads like an M-16 unlike most other sci/fi games EVER made.
All rare weapons are "artifacts". It's not just a +5 sword of awesomeness, it's a unique weapon with its own backstory (well 90% of the time) and lore.
It's not "red versus blue" each faction has a complex web of allies, enemies and people they don't really care about. PvP is not a matter of "go get the green guy/go get the elf".
Air vehicles. Need I say more?
one of the best construction/tradeskill systems in any MMO ever. Not as fiddly and painful as Star Wars Galaxies, but not as over-simplified as most latest-gen MMOs.
Tradeskills are still a vital part of the game even at cap. It's not a matter of "use good crafted weapons until the lich king drops a +7 sword of asskicking and use that from then on." ((Okay sure WoC breaks this a bit but WoC is rare right now)).
Anyone else have any others?