I use the Sonic Defenders EP3 (the link is in german, but you get the idea
http://www.sonicshop.de/De/Plugs/Sonic-Defenders-EP3-SonicSet.asp). Tried the usual cheap stuff and all and stuck with these, since custom fitted ones are too expensive for me. These cost about 20 pounds and last me half a year or so before they feel too weird.
These have a good fit once warm, I can even wear them during a 10h festival day without too much discomfort.
Filtering whise they are not perfect, but they are very close to just turning down the volume and as a plus they cut the noise (certain frequencies that just sound bad (like noise) or hurt....I never really know if most people donīt hear these or what, but I always tell myself that my hearing is just still a lot more intact than most peoples and a little more trained at least, hearing protection be thanked).
Always suprises me again how well you can hear speach through these with everything else turned down so much.
What always baffles me is how few people use hearing protection. At regular concerts I feel like I am 1 in 100 who uses one and at my job I do live mixing in a small room where you gotta set the sound level to the not amplified cymbals and let me tell you, that can get loud as shite (got bagpipes next weekend, can already hear the complaints), but just about 10% of the people there use hearing protection, which is really beyond me, as the levels there are really pretty $%ed up, especially the high frequencies.
I am always amazed that I donīt have to scream at them...
Then again I notice a lot more sound wise then them (from stuff in music to that high pitched noise of old TVs which a lot of the kids younger than me canīt hear anymore) and I never know how much of that is training and how much is just being able to hear frequencies.