I've been through the Ts-400, SuperTips, Shure Olives, and MEElec triple flanges. I started out with the leftover Olives and I've gone back to using them after trying everything else out. Here's a quick summary of my impressions of each:
MEElec triple flanges: Worked alright but tended to lose their seal after 10 or 20 minutes. Sounded good but once they loosened up and lost the seal they lost all bass. I found the triple flanges to be really uncomfortable after a while, so I only managed to use them for a couple of days. This is probably just a case of them not fitting well for me. If triple flanges are your thing I'd imagine they would work well.
SuperTips: The ones I received were so bad I couldn't use them for more than 10 minutes. Both the gel and the foam tips were much stiffer than the Complys and Shures and didn't seal well at all. They get 0/5 stars from me as they weren't even functional in comparison to the others.
Comply Ts-400: Pretty good, but I found they wear out faster than the Shures. If I could get tips that were made of the Shure foam but built in the shape of these, I'd be in heaven. They're quite comfortable and sound about as good as the Shures, at least until they wear out. They isolate decently, but not as much as the Shures. The biggest problem I had with them is they were a bit too loose. They would sometimes pop off the headphone stem when I rolled them up to put them on.
Shure Olives (medium): These are what I started using when I first bought the GR07s and they're what I've finally settled on again after wasting a bunch of money on other tips
They may be just a little more muffled than other options, but they isolate much better and the bass is fuller. I tend to listen at low volumes so I appreciate being able to hear bass at low levels as well as the additional isolation. I've found the best way to stretch out the Shure core is to use a pair of tapered plastic chopsticks. I throw each tip on a chopstick (narrow end first) and slowly push each tip about a third of the way down. I do it in about 3 increments and the plastic will slowly stretch out. After that they pop onto the stems pretty easily. I've found I have to use a utility knife to get them back off sometimes, but that's no big deal. No problems with them accidentally popping off either
So my personal peference is Olives -> Complys -> MEElec if you want triple flanges -> don't get the SuperTips.