I find it amusing that close to 150 pages into this thread I'm seeing it pointed out that everyone's ear and ear canal is shaped differently. This is of course the most relevant consideration when making and receiving suggestions about ear tips. One must try things for themself. There's simply no way around that.
Having said that, here's my two cents.
I've spent over a hundred hours over the past five years researching and trying ear tips. It took a few years before I even "got it" that seal is everything, after which come tone and comfort. It was the experience of having gotten a good seal that opened my eyes (ears).
I'm not a fan of extremes. I'm using the Shure SE425 because they're touted as being neutral (and I haven't been able to afford the SE826 to try them out yet -- though I did try the SE525 and returned them right away because true to the reviews they were way too bass-heavy for my liking).
And I'm using the Shure TW2 BT. I had been using the FiiO BTR5 and loved it but the freedom and convenience/customizations of the TW2 more than justify using them, and SQ is darned close to the BTR5 (TW2 doesn't do LDAC, BTR5 does).
I don't have a lot of time for rolling up foam tips and waiting for them to expand but I was living with it when I thought it would be worth it.
Now, however, I'm using silicone tips.
I like my bass to be there. I like the mids and highs to be there, cleanly but smoothly, nothing too muffled or too imposing at any level. I seem to have found what I'm looking for now.
I found foams to be just a bit too muddying of SQ (Westone Audio, Comply Professional). I did determine that if I do use them I'll use a size large enough to seal and will simply slide them in, perhaps also pulling up the ear to open the canal. No more rolling them up first, and I ended up wondering why I ever did that or anyone suggests it.
Tried Shure foam and silicone (and may try them again -- it's been a while). Tried Westone Audio Star silicone and like them very much!
But now I may have found home. (Well, wandering neurotics will always do some tip rolling in search of the perfect sound and fit, I guess, but I'm happy right now.)
SpinFit!
For the Shure SE line, get the SpinFit "CP100 Plus." (It comes with adapters to fit the stem.)
The design and materials are remarkable. The silicone dome is thin and soft and that seems to lend itself to fitting to the ear shape and sealing in a way that others didn't come close to doing. It seals so well that the dome "reverses" when I pull it out of my right ear!
(Note: When trying sizes one must try and up and down size to get the best fit -- and that it's common for the left and right ears to be different enough to justify considering different sized tips for the left and right ears!)
The design of the SpinFit includes a "pivot" feature, allowing the dome to pivot off of the axis of the IEM stem so it fits the direction of the ear canal without being limited to the shape of the IEM and its stem! That seems to make a huge difference! One way I tested the different kinds of tips was to notice how readily the seal maintained when I smiled or opened my mouth/jaw. All others without exception lost bass/seal to varying degrees -- but son-of-gun the SpinFit maintained the seal/bass no matter what!
And overall SQ is just the right sweet spot for my liking, acknowledging that there are always tradeoffs along with the benefits when trying any given tips. It's my Goldilocks. Plenty of bass but not suffocating, good range through mids and highs, and no unpleasant sharpness in the highs. Everything is pretty balanced, clean, and smooth. (This is how a totally-NOT-an-audiophile explains things.)
Happy camper.
YMMV.