I guess the difference is really one of how much experience do you have. Me, I'm at the latter end of my youth; my experience is soured by experience; I am not put off by money grabbing aggressive approaches of the marketing guys, I'm still more inclined to favour the personal touch as portrayed by Elecsa. I quite like Napit but they a bit out of reach when it comes to what I want.
I learnt my electrics something like IEE 12/13th Edition.. in the 70's .. gave up due to being out of touch and I then decided to become competent again and I must say I quite like the new regime
When it comes down to it I think it doesn't really matter who you join up with, just go by personal taste. At the end of the day you will become experienced and worthy by which I mean your Clients will be your advert and your recommendation! These companies that we have to register with are not to be our masters so much as our servants in time of need & like all good servants you have to pay them to keep them handy