Vanu by just a little bit, but it's not as bad as it was a few months ago. I choose Vanu because they have the only really good anti infantry tank secondary and don't hesitate to use it. I don't think they should change it, they should just give the other empire specific AI weapons large magazines so they can be used to hinder infantry at long range in the same fashion. A large magazine could even be an over buff for the marauder; hard to tell with the C85 because it would still be a shotgun at long range. To be honest I'm not too familiar with either. C85 is still thought to be quite bad so I never get to gun one and I don't play my TR character except to login for welfare certs.
People still complain about Orions but the flavor of the month seems to have switched back to Liberators and to a lesser extent Magrider PPA spam.
The prowler could use a boost, I think maybe if it was faster it would be better. It has lockdown but it's an odd fit with the fastest empire specific tank. Maybe it could be changed to lock the turret horizontally in a fixed position while still being mobile.
The TR max with chainguns isn't so great beyond infantry slaying, but with pounders it's pretty good at multiple roles. Their max lockdown can be ok in some narrow circumstances like shooting out of a doorway that has a limited line of sight inside like that set of stairs leading up to the left of the SCU shield gen in a biolab but it's asking for a HA to rocket you there, or a C4 from above most places.
I like the Reaver but I use Dogfighting frame which seems to have slightly less of a problem with ground fire. I only have it because I picked it up early. It works okay with stealth armor because it's easy to get 10m from someone's tail if you aren't autospotted and stay on it while you aim for two magazines of airhammer. Other frames are probably better.
Airhammer is the worst of the AI noseguns for AI due to only being okay at close range and unusable against infantry at more than that. The upside is it's pretty good versus air. This is unlike other empire's anti-infantry noseguns, but ONLY if you can get close is it useful. It does a lot of damage to libs but a competent gunner will have no problem nailing you if you aren't dodging when the lib turns it's belly to you. It can be used at long range to plink libs and galaxies because they are big, slow, and much clumsier in the air than esfs, so you can at least tap them from long distance with many of the pellets while you fly closer. Don't expect to win a hover fight with esfs using it; you'll want to try to get close and that means trying to dodge bullets as you fly towards them as they hover and shoot at you. Your best bet is staying in flight mode and afterburning with stealth armor onto someone's tail while they are unaware of you or away from enemies that have spotted you. If there are friendly air in the area and you use dogfighting frame like me, you can try out turning an ESF trying to nosegun you until they are intercepted. Otherwise you should afterburner with airhammer away to friendly lines if you are being shot at.
The Jackhammer is a great gun, if you use NC heavy often you should get it for use in buildings. I don't use it much but it's great as it has enough range to go across a room with damage unlike a normal pellet shotgun. The Lasher is also great but for different reasons. It's probably the best infantry usable suppression weapon in the game. It's really good in large numbers because you just can't go near doors covered by more than one lasher to pop in and out.
Liberators seem a little too strong now, but not by too much. The skyguard/liberator relationship seems a little off in the liberator's favor because liberators will usually be able to disengage whenever they feel like it's a good idea while a skyguard without a building or cave to hide in is going to die to a tankbuster lighting them on fire with one magazine and then the gunner taking them out. Skyguards and other AA stack really well though because in addition to a Skyguard being harder to spot against the ground than aircraft in the sky often aircraft won't have time to find cover from them before 'melting' if the AA is concentrated enough. I guess I'd make the gunner's screen shake when being hit by flak. If that's not enough of a nerf, I'd make the Liberator more maneuverable to help avoid flak and make tankbuster do less damage as a consequence. The belly guns seem fine to me except the C-75 Duster, which by all accounts is by far the worst of the bunch. If it's that inaccurate it should have a huge outer radius that doesn't damage armored vehicles. If that makes it too good severely limit it's ammo pool and resupply time so it has to resupply very often and for longer in exchange for being very effective when not flying to reload.