ACS for me. I used ER15's for 10 years and have now switched to the PRO17's.
Of course ear plugs change the sound, but not as much as the issues you get with hearing loss and IME the differences caused by ear plugs are easy to deal with.
What's the alternative? Massive tinnitus, giving up gigging, hearing aids and partial (if you're lucky) deafness. Great choices!!
All of these problems are preventable. If you're in a gigging musician then hearing protection isn't a choice it's a necessity.