Yep the following are the ones which are the most popular (in my order of preference) if you go through the awesome CK10 thread:
1. Sony Hybrids (Original/Compatible) (My favourite)
2. Monster Tr-flanges (Original/Compatible)
3. CK100 Foamies
4. Shure Olives/Tri-Flanges
and then there are a whole bunch of other mentioned by AudioDwebe.
If you want the comfort/sound closest to the stock tips, go for the Sony Hybrids.
Here is the list of compatible tips (taken from the CK10 thread - sorry I have no idea where it is from - I just had them saved in my notes - credit to the original poster)
Quote:
List of compatible tips:
-Altec Lansing tri-flanges
-Audio Technica foams (ER-CK100)
-Audio Technica silicon
- Complys (tstarn06)
-Etymotic tri-flanges (googleli)
-Etymotic Glider foam (average_joe)
-FutureSonics Atrio tips (dfkt)
-JVC / Victor FX500 foams (shigzeo)
-Klipsch gel tips (tstarn06)
-Monster Cable tips (average_joe)
-NuForce foams (shigzeo)
-Phonak Audéo PFE tips
-Shure tri-flanges (mp3)
- Shure Olives (de-cored) (a bit loose)
-Sony Hybrids (EP-EX10A) (ljokerl)
-SoundMagic foams
-Ultimate Ears silicon (james444; can also be modified with Playaz/Xears orange foams stuffed underneath)
-VSonic foams (ljokerl)