I played VS when I started and enjoyed using their vehicles and guns, though I hated their spandex purple uniforms so much that I wanted a change. The VS players seemed pretty decent overall (general attitude).
I played TR and fell in love with their guns for different reasons -- spray and pray actually worked more during panic fire moments and they sounded/felt like GUNS. I didn't like the graphics of the guns, but they felt good to use. I did really well with them, too. HATED their community on Mattherson. My first hour was staring in shock at my screen watching the trash talk, then listening to dozens of players screaming at each other over prox chat with so much rage that I didn't even want to play. I'll try again over the weekend maybe.
I played NC and ... well, the gun models are sweet (along with the vehicle models), but they don't quite FEEL right. Maybe it's the sound effects. Maybe it's getting used to the recoil -- hopefully that's what it is, because I'm a little underwhelmed right now. Still not sure about their community on Mattherson since the big update hit and everything is crazy anyway. Mid-long range combat was okay with careful bursts, but nothing I couldn't repeat with the other factions.
I guess nothing really stands out to me when it comes to NC guns. On paper it looks obvious: more damage per bullet, more recoil. In practice it doesn't seem that clear. Eh, I'm on BR 9 or something on my NC. I'll keep practicing.
(Side question: is the Phoenix fun to use? Not asking if it gets lots of kills since I don't care about K/D, but asking if it's just fun to own and worth the SC.)