I guess it depends what you want to acheive from a harness - the gencon appears to be something which relies on discomfort to work, which isn't something I would personally use, especially as the loop around the neck also tightens, which seems like a slip-lead to me (and while some trainers use slip leads for training loose lead walking, the apdt does not support this as it can cause injury in non-expert hands).
I'm also not a great fan of headcollars myself, as there is potential for accidentally jerking a dogs neck if they suddenly lunge (though I know some people have great success with them).
I have a T-Touch harness, which is very similar to the Mekuti, which both work along the same kind of principles as the Halti harness - the idea is that you have 2 points of contact so that you are able to counter the dog's pulling, rather than pull against them, especially as you can attach one end of the lead in front (or bring the lead around across the chest and then attach at the other side creating a balance leash) which means pulling is just counter-productive, as the dog gets turned back towards the handler.
Honey isn't much of a puller when her mind is on the job, but can lunge occassionally (normally at cats) and I find the harness absorbs that pull without causing her (or me) discomfort (I generally only attach one end of the lead on our normal walk, but would use a double end if we were anywhere more unfamiliar and so more exciting).
I think with harnesses etc it's very much a case of what works for one may not work for another, though, so a little bit of trial and error does seem to come in to it.
