I haven't tried the Sonic Valve but I've had both the others. I've also had two pairs of electronic ear muffs but just can't get on with them. I find they clatter against the stock when I'm mounting the gun, which I find very off-putting.
I bought a pair of Emtecs at the Game Fair in 2006 and swore by them until I lost one this season....then I just swore. I found them comfortable and effective. Sadly Emtec no longer had the impressions of my ear canals so I couldn't get a replacement without going in for another measuring session.
Instead I bought a pair of the CENS ProFlex Digital 1. If anything they are more comfortable still, but that could be because the ear canal changes over time so the more recent impression is a better fit, or that the silicone they use is a newer blend. The electronic module is great, though it does mean I can now hear the comments of the guns further down the line
I did get the feeling they stick in a load of "stuff" to help justify the price, which I'd gladly have done without (baseball cap, aluminium case, etc). That aside, I'd happily recommend them and would rate them above the Emtecs, but that's not really a fair comparison with earplugs produced some 8 years apart.
If you buy the CENS Passive you can buy the electronic insert at a later date if you decide to upgrade, which might be useful. When I bought mine I did the reverse - I bought the electronic module but also bought the passive inserts. This is because I sometimes use earplugs when flying, which I do a lot for work.
willie_gunn