I was using the Klipsch S4i and had good noise attenuation and great sound quality with the Autocom. More recently I switched to the uClear 220 BT units and use the uClear noise reduction earbuds with them. I think you will be very happy using earbuds with almost any degree of noise isolation. You still hear important traffic inputs, but the sound quality is greatly improved.
I would look at any prospective earbuds with an eye on the sound quality reviews. For me the Klipsch was nice because the oval shaped silicone was a lot more comfortable for extended use. Whatever you select, you will be using it for long days on the bike, and any of them will be better than helmet speakers. BTW, I left the helmet speakers installed, and can plug in either speakers or earbuds as I wish.