intense barking at specific dogs

Barking is a frustration behavior.  I think all you have is an extremely social, if slightly fearful dog.  What tells me that is that your dog is fine off leash (NOT aggressive) and that he would rather leave than fight (probably just wanted to play).  Please stop using the choke - pain makes leash reactivity worse!!!  Instead, get him an Easy Walk Harness (www.premierpet.com). He won't be able to pull you, and he won't be damaging his larynx.  Then, grab a copy of Ali Brown's book, "Scaredy Dog".  In it, you will find instructions on how to keep his attention when a distracting dog comes by.  HTH

Thanks!  I will check out the leash.  We don't think of the choke as something to use for discipline.  we just like having the confidence that he can't pull out of it.
 
It seems more agressive than playful for sure what he's doing. 

So he did it again today.  Can anyone recommend what my response should be when he sees these other dogs on the street or in my building lobby and he freaks out?  Should I be trying to calm him and soothe him?  Or should I correct him firmly and loudly in the deep discipline voice?  I really need to train this behavior away even if it means more obedience school.  I don't like the fact that he gets so out of control when he sees these specific dogs.

I would not do either of those things.  Calming and soothe him will only reinforce the undesirable behaviour and make it more likely to happen again in the future.  A correction is likely to cause/exacerbate a fear/anxiety problem. 

Desensitize him slowly to his triggers.  Use treats or a favourite toy to get his attention and keep it on you when you see the other dog and then do everything you can to keep enough distance that you can continue to reward him for the desirable behaviour (heeling or sitting and "watching" you).  Walk the other way, cross the street, change direction, quicken your pace (but stay calm) ANYTHING to keep you far away from the other dog.    It really isn't any good saying "sit!", "heel!", "leave!", "watch me!" "No!" etc when he is already barking, lunging and in close proximity to another dog, your voice will just be a background buzzing to him and you are letting him practise ignoring you!  Better to build up to that level slowly
Over time the distance you will need to keep will get less - don't rush it. 

NB - Keep the reward value HIGH (think liver cake not kibble!  If he is toy motivated make it a special toy that he only has access to occasionally - you can super-charge it by playing short and highly exciting games with it and put it away while he is still "on a high") 

It is helpful if you can keep him away from his triggers for a few days, even a week while you stay at home, refresh "heel" and "sit" as well as refreshing/teaching "watch me" at home in a low distraction environment, then when out but in quiet areas/times of day away from his triggers initially.  Keeping him away from those triggers will allow the stress hormones in his body to dissipate which will make him calmer and easier to work with. 

During this time also implement NILIF (and if you already do, redouble your efforts) so that he is convinced he has a competent "leader" at his side, that you will take care of him (not the other way round) and that it's worth checking in with you when he is unsure and following your example.  So that when you are in a position where he is barking and lunging, stay as calm as you can, remain aloof and unbothered by the supposed "threat" and remove him from the situation.  If he is convinced of your "leadership" he should become more responsive to you and when you are calm, he will follow suit.

A good anti-pull device enable you you handle him effectively and this in turn will boost your own confidence which will have a profound effect on him.  The harness is a very good idea, I would DEFINATELY steer clear of head braces (like the gentle leader or halti) because of his lunging - it could do damage to his neck muscles/vertebrae.  I'd also steer clear of a choke for the same reason - they are only really suitable for a dog that can (and will) walk on a fairly loose lead and even then care should be taken that they are properly fitted, put on the right way and any corrections given are sparse and precisely delivered.  (Best left to a professional IMO)

This is leash reactivity. He's totally out of control, and once he goes into his frenzy nothing you do will have much impact on his behavior. Certainly you don't want to discipline him (will get him more worked up), or try to soothe him (tells him he's doing what you want him to do). The way to fix leash reactivity is to not-let it happen-- sounds silly, right? Basically you first teach the dog to look at you when you call the dog's name. Do this in a quiet location. Once he's doing well, move to more noisy locations. And then try it while you are a long distance away from the problem dogs. And gradually get closer, rewarding for being calm and being able to look at you when you call his name no matter what is going on around him. If he goes into a frenzy, you've gotten too close to the trigger dogs for his level of training. If he does go into a frenzy, cheerfully call his name, do a sharp about turn (to get the dogs out of sight), and march briskly off.
 
Get rid of the choker. It is damaging his neck. If you're afraid of him backing out of a collar, they make a special kind of collar for that-- called a martingale. It tightens a limited amount. You can get nicely padded, humane martingales.
 
The fact that you live in the building with the trigger dogs is going to make this very hard for you at first, avoiding full-on frenzies.
 
You might want to do some reading-- Click to Calm is a book on exactly this subject.

Great advice.  Also, instead of just standing there tugging on the leash, you might want to think about exiting the area really quickly, and just reward him for catching up to you.  It is almost impossible to do anything about this behavior in close proximity to the "trigger", in this case - other dogs, but you can work up to it.  "Click to Calm" is a great book with good step by step instructions.  It wouldn't hurt to take a few lessons on clicker training first if you can.  To find a trainer near you:
www.clickertraining.com
www.peaceablepaws.com
www.ccpdt.com
You can find free lessons at www.clickerlessons.com
Free videos to watch at www.clickertrainusa.com