Ok - I have four sets in rotation right now. A quick summary of where my listening is at, and tips that have worked for me
1. Nuarl 6P - by far these are the most natural, enjoyable set to listen to for extended period, regardless the source. I find myself loving the sound,
Connectivity : Rock Solid.
Comfort & Fit: Surprisingly easy and comfortable to wear despite the large form factor and relative heft. The provide excellent passive isolation.
Tips : Spinfit CP 360s provide a good fit for me
2. Maven Air-Xr Qi - these are heavy on the bass, but provide an enjoyable soundstage. If they had an app, I'd EQ down the lows.
Connectivity : Rock Solid.
Comfort & Fit : Super lightweight, great isolation. Easy to grab and go on the bike.
Tips : After trying spinfits, foams, I settled on the oval silicon tips they ship with, which provided the best isolation and sound for me
3. Libratone Track Air + - once I got a good fit they sounded very aggressive, perhaps a bit metallic, definitely bass forward even with the neutral EQ setting. The isolation even with the best tips I found is quite poor though so it sort of requires ANC. The app is bizarre in how you dial the ANC in and out - Smart mode works well except when you are walking when it detects and puts in too much passthrough
Connectivity: Prone to occasional dropouts compared to my other units
Comfort & Fit : These were a nightmare for me to find something that worked. The tips they ship with provided bad isolation and given the strange shallow connection point they tended to smoosh against the surface of my ear, so I looked for something with a little longer interior barrel. Once in, they are so light you can forget about them though
Tips : Spinfit CP 100z's -- after trying 360s', foam, shipped tips, the tips I had accumulated from my other IEMs, these are the only ones that stayed attached, and went deep enough to provide reasonable bass and isolation. All other tips for me sounded flat. I wonder if this is why the default sound signature feels like it has overly boosted lows when you use a good 3rd party tip
4. Mifo O7 - I've written of these before. Want to like them but the bass distortion is absolutely horrible even at low volumes, much worse than others. I am trying a replacement and I'll report back with what I found ( try Mona Lisa by De Staat for almost constant clipping in my unit)
Connectivity : Totally solid
Comfort & Fit : More comfortable than the Track Air +s as they have a more rounded form factor despite being slightly heavier. No complaints
Tips : Same tips work on this as with my Nuarl 6Ps - the CP 360s are fine. Good isolation, no complaints
So in order of goodness :
Nuarl 6P >> Mavis Air-Xr Qi > Libratone Track Air +
all are perfectly good sets but the only one I think that even approaches regular IEM sound is the 6P. The Xr is a terrific compromise set, the track air + is skewed mass consumer sound for pop I think, and the jury out on the O7s until I get a replacement.