I am a compulsive underwear buyer! I am always on the lookout for my new favourites, and I have tried everything. Here are my discoveries:
I am going to be way in the minority here, but my hands-down favourites for comfort are low-rise cotton bikinis. I currently have a love affair going with the Calvin Klein "Modern Cotton" bikinis that kkards posted above. They come in all different colours, but always a broad white waistband, like the men's. I like that.
Bikini underpants almost always create VPL with thin, tight pants or clingy knit skirts. I deal with this by generally not wearing those kinds of bottoms! No yoga pants for sure. I do sometimes wear jeans that are tight enough to show VPL, and in that case, I wear boyshorts. The brand doesn't seem to matter, but what does matter is whether or not there is a centre seam along the back. If there is, they will crawl up my buttcrack.
Also, boyshorts with a bit of leg coverage will bunch up at the tops of my thighs when I pull up my tight jeans, and I have to sort of wiggle around and straighten them every time I go to the bathroom. But these ones are also less likely to migrate crackwise, so it's a trade-off.
I find that synthetic fabrics, especially on tight boyshorts that crawl inwards, encourage itchy skin conditions. For this reason I try not to wear them every day. My body seems to be able to tell the difference between all-cotton undies and ones that merely have a cotton crotch. I know this isn't true for everybody, though.
Thong underpants are horrible. They irritate my buttcrack and tailbone and look appalling to boot! I know some women swear by them, but for me they simply don't work. Plus, they require much more aggressive hair removal than I'm willing to endure.
ETA the Calvin Klein Invisible Hipster briefs that Marilyn posted above are the WORST I have ever worn, in terms to bunching up in my butt! A fine example of how what works marvellously for one woman is completely useless for another. You really just have to experiment.