Hi, my dog is an 18mth old Boxer/Staffy cross, adopted from a rescue centre. I thought I would offer some support and hopefully helpful suggestions. After being pulled over flat on the footpath as my dog was performing at dogs across the street we introduced her to a halti. Initially this was only used for a short time and without leaving home. She didn't like it at first and managed to slip it off but very quickly has become used to it and sits nicely while waiting for it to be put on. We now walk with the halti and a lead, and a second lead attached to her collar. This has helped immensley in terms of control and being able to stay on my feet! Unfortunately it hasn't helped with the reaction to other dogs, cats, skateboards etc. We have worked with two excellent trainers and made some progress. Our girl has a very, very high prey drive and views everything as hers to play with hence the over-the-top jumping, lunging and screaming on lead. We have followed carefully all the alpha dog techniques in the Sit-Stay-Fetch programme with good success. Around home and if out without distraction she is very obedient, respectful and will respond to requests quickly. However, in the situations with dogs etc she seems to zone out and we become invisible. Just lately we were able to have a short session with a top trainer who is no longer training but offered some hope in that he felt she would improve with patience and persistance on our part, and assured us she is not aggressive. So far it has been seven months, which isn't really that long but seems like years! His suggestion was to never actually pull back on the lead. When she starts performing just hold the lead firmly and allow her to go to the end of it but don't give anymore, also resist that urge to pull back towards you. If possible, lower your height, so squat down if you can keep your footing, and call your dog, with a treat in hand. Immediately your dog returns to you, feed the treat and quickly move on. A pocket full of treats on every walk is a good idea. This was two weeks ago. So far we are having a glimmer of success with this. Because the leaping, barking/screaming etc is so full-on we haven't been able to stop and drop lower everytime it happens but regularly during a walk whoever is holding the lead (my husband or myself only) stops, lowers down and calls the dog without pulling on the lead. She is responding really quickly to this now as there is always a treat and lots of praise. The walk is then resumed. The performances still happen but I think she is calming down much more quickly afterwards.
Interestingly, when we meet face to face with other dogs she is very well behaved and not at all aggressive but once either we or the other dog moves away she starts performing and sounds like she wants to kill the other dog, which isn't the case. It's a dreadful situation as it makes other pet owners want to give us a very wide berth and they go by tut-tutting about what an aggressive dog we have. We have a doggy friend that we sometimes meet at the park and walk along with quite happily, but if another dog is seen within the area we have a performance.

Our girl seems to be a natural alpha and very intelligent. Therefore we can't give one inch in terms of who is in charge, especially when it comes to getting on furniture, who goes first through doors and gates, and feeding first. It is hard because she really loves to snuggle up and I would love to have her curl up on the couch with me, but she has proven give one inch and she'll take a mile.
I really hope you can glean something out of our experience to help you. Don't give up and isn't it great to know you're not alone with this problem. All the best, would love to hear of progress.