Only perks I don't use extensively are commando and survivalist, so I don't know much about those two.
Support: I use increased reload, salvo, tight choke, resupply, and barrage. I never used high capacity mags because it's quite easy to work with the number of shots in all the shotguns. 8-20 is enough to kill most of a horde if you aim well. Fortitude I believe is only for supports that have issues dying. Increased damage will always beat it. I did run increased pen when I was lower in the skill set, but once you get around 20, armor piercing shot becomes redundant. There's also no need for concussion rounds because shotguns have enough stumble power with them. Plus, you get extra ammo by selecting resupply pack along with being a team player. Lastly, just like armor piercing shot, there's no need for increased penetration, since you get 500% of it at 25. Might as well put all those rounds to use and kill that scrake during zed time.
Berserker: Both lvl 5 skills are good and offer different playstyles. I still pick skirmisher because zerks need to run fast and the added health regen is great. It's also great when paired with vampire, so you'll get 6 health back while killing stuff instead of 2. Butcher is fine if you don't need to worry about your health much, but vampire is great overall, even when there's a medic around. He can't keep his thumb on you all the time. For 15...Parry easily beats out resistance. I explained this in another topic about zerk skills, and while parry offers resistance for 10 seconds, it offers a better combo than overall resistance. At 25, you'll get a 35% damage reduction with resistance, while parry offers 55% plus 60% more damage dealt for 10 seconds. The fact you can chain parries means you'll be hard to kill and kill zeds a lot easier for a good minute. At 20, it's a toss up depending on what weapons you use, but I believe smash is better since you'll be using that a lot to put down most zeds. At 25, zerker rage is good with dreadnaught, but Spartan beats it out big time because instilling Chaos Control during zed time is way more effective than letting zeds retreat.
Demo: Both beginner skills are good, though once you get high enough in the tree, that extra damage doesn't seem like the best idea with how slow the demo reloads. 50% more damage sounds good at 25, but with how fast zeds are moving in HoE...I just want to put more rounds down range. Plus, stumbling zeds around is fun to watch. Same goes for extra rounds. 21 shots for an RPG sometimes isn't enough. Also, I found out the high impact rounds only kick in during the initial impact. It does NOTHING for the explosive effect. Also, it generally takes 3 rockets to off a FP, so those extra rounds come in handy. The competition between the lvl 15 skills is a joke. Who in their right mind would take a skill that LOWERS damage dealt over a skill that makes sirens a non-issue? Even the increased blast radius isn't a saving throw. Lvl 20 is the same deal. If you have good aim, you can down scrakes in one or two hits with the RPG. It also makes the M79 blow almost any non-big zed if you strike the head. Now, at 25 I have seen a few demos pick mad bomber over nuke, but nuke does higher damage overall and lasts after zed time with its poison cloud. Also, Nuke is much less likely to kill you than mad bomber if you get swarmed.
Pyro: Since I always go after trash instead of the big zeds, I take extra fuel, ground fire, zed shrapnel, firestorm, and pyromaniac. That 35% damage increase would be good in some cases, but I'd rather have 100 fuel points than 50 for that DIY flamethrower (plus 200 for the real flamethrower is a plus). BBQ IMO is a bit pointless since most zeds running into your flames will die off quickly, and ground fire can drop any trash zed easily. Napalm is also pointless because zeds will be grouped together anyways when you set them alight, and zed shrapnel not only does damage when a zed explodes, it can also knock down the biggest zeds. Heat Wave is good if you intend to go after the big zeds, but I'd rather keep any zeds from getting close. More room to breathe = more ground fire. Also, more damage at zed time looks pretty nice, but not burning any fuel is more advantageous in the long run.
Gunslinger: My aim with pistols sucks at times so I tend to hip fire a lot. I think steady is good if you're accurate, but quick draw helps when switching weapons and for hip firing. Plus, you get a headstart at moving quickly. And because I hip fire a lot, bone breaker for that extra damage is good. I find line em up to be pointless since GS is a mobile sniper and i'd prefer to reload quickly, especially if I have to deal with a big zed. Skullcracker is really good when taking on big zeds, so you can outrun that angry FP and keep nailing him. I tried knock em down once, and it only worked well on scrakes. Tried it on FP....not so much...
25 is good on both sides. Firing quicker so you can kill something is good, but not wasting the small ammunition pool that pistols have is even better IMO. Also, if I fire to quick I'll end up missing shots, and whirlwind lets me keep my aim steady so I can keep hitting those heads.
Sniper: Both sides at the start are decent, and it depends on whether you need to move around a lot. If the team has a solid front line, I'll pick sniper, but if I gotta move, marksmen is better. For lvl 10, regardless of the skills, I pick stability because there's always a chance to crouch and fire. Ballistic shock I think is only meant for big zeds, and even then it's kinda random to use. I pick tact reload with all perks, so theres that. At 20, I think it depends on what weapon you're using. If you're using the railgun, then dead eye is better, but always prepared is better when using the M14. At 25, Assassin with the railgun can one shot scrakes, and the stumble effect doesn't always work.
SWAT: Heavy armor is good throughout the game, since you don't have to worry about your health until your armor runs out. Tact reload for all perks at 10, and then I use ammo vest, because SMGs have a rather abysmal ammo pool. Suppression rounds is pointless since zeds stumble quite a bit when hit by SMGs. 20 is a toss between slowing zeds or having more armor. Might depend on whether you're getting hit a lot, but I chose more armor since that's more time I don't have to worry about my health. Never tried cripple, though if they changed it so where head shots were most effective than the legs, I'd pick that. At 25...just about everyone and their grandma will pick rapid assault. It makes killing those big zeds or horde much easier. Battering ram is very situational and mainly for funnies. I always laugh when I see a SWAT knock down a raging FP in zed time.
Medic: All left, with only tact reload for the right. Left skills are for team play, right is for solo. I don't know why some medics pick poison rounds in a team setting, when your buddies could be dealing extra damage. Same goes for increased medic weapon damage. Compared to other perks weapons, medic guns are rather abysmal in dealing damage. Only exceptions are when they're used by another perk and the highest 3 weapons. Your team would be better off getting some damage resistance than you trying to be a battle medic. Also, I don't pick resilience because you get health as you heal others. I don't get why some medics pick that and drop to 50 just to get the most out of it. If one siren screams at you, you're gonna be dead very soon, and it's better to have 125 that you can keep up very easily by doing your job. At 25, airborne agent is way better since if you get swarmed, trash zeds will get poisoned and die quickly. Zedative is only useful in solo play.