I've tried the EW300 and it's good, but IMO, does not justify the price. I've also used our sound guy's Audio Technica unit (though I don't remember the model) when my Galaxy 1100 was in the shop. The rest of the guys in my band use the Carvin system, though I haven't tried it myself.
I did not like the audio technica. Tiny DIP switches in the pack to turn anything on/off? Are you kidding? Luckily, I had a fingernail clipper at the gig and used the point on the file to flip them into stereo. I also the sound was lacking in the low mids.
The Galaxy 1100 is the best I've found so far, but it's not without caveats. I bought it second hand and initially had some issues like, signal popping, only get 2 sets out of a battery change, etc... Then a sound guy got a cable stuck in the back of it and I had to send it in for replacement. They replaced the entire board because that wasn't the only issue I guess. Now it's awesome. I get more than an entire night out of the batteries, it sounds great, and most of the popping issue has gone to the wayside. I should note that I now wear this on my actual belt, rather than my pocket, and I stuff my shirt under it. It doesn't have a solid antennae, so my when my shirt was hitting it, it would pop. Works great!
With ANY in ear system, watch how hot the signal to it is. The limiters are generally brick walls, so it's easy to slam them with signal and not get "enough" of everything or get pumping when it's just guitar and vocal, then the whole band kicks in and it distorts to hell. With a few units, you can turn the limiter off, but I don't think I've seen one with an adjustable limiter.