If you're looking for a smartphone with a motorized flip camera, your choices are pretty limited - it's either the Zenfone 6 here, the Oppo N3 from way back in 2014, or the Samsung Galaxy A80.
The Galaxy A80 will deliver the flipping and the pop-up mechanism is motorized too, but due to the nature of its design, you won't be getting the automated panoramas or the waist level shooting capabilities, so there's one in favor of the Zenfone's Flip Camera. The Asus offering has the more potent chipset (S855 vs. S730), and it's got the dedicated microSD slot, while the A80 doesn't have one at all. The Zenfone also has a headphone jack and stereo speakers, both missing on the Galaxy. The Galaxy does have a superior display with a fingerprint reader underneath, and it'll charge faster, though it won't last quite as long. The Zenfone is more affordable, however.
On to the conventional camera phones that compete in terms of pricing rather than rotating cameras now. The Xiaomi Mi 9 quickly springs to mind - it offers a trifecta of cameras on its back, including the telephoto that the Zenfone is missing. The Mi 9 has a superior displayand doesn't look half bad in the endurance match-up despite the much smaller battery. The Xiaomi is lighter and slightly more compact, but lacks a microSD slot. You do maybe stand to save some cash if you go the Xiaomi way, depending on where you are in the world.
The OnePlus 7 (non-Pro) is slightly more expensive than a Zenfone 6, base model against base model, though you do get twice the built-in storage on the OnePlus phone. The Zenfone does allow you to expand it, however, unlike the 7. Asus will also give you the better cameras including an ultra wide perspective that the 7 is missing. The OnePlus does have the better display.
If you're willing to wait it out a bit so the price can drop as it typically does, the LG G8 ThinQ could potentially make sense, particularly if you're those parts of the world where the G8 comes with 3 cameras on the back. Regardless of region, the G8 is IP68-rated, so that's peace of mind the Zenfone can't deliver. The G8's OLED display is brighter but, for a change, even more off-key than the Zenfone's - pick your poison. Ah, there's the matter of the G8's comparatively dismal battery life.
Come in for the cool motorized camera, stay for everything else - that's pretty much what the Zenfone 6 is all about. That is, if you manage to look past its not quite stellar display - other than that Asus has managed to pull off quite the package for a very reasonable price.
Easily some of the best possible selfies you can get from a smartphone today is only the flip side to an excellent camera experience across stills and video, in daylight or at night. And you'll have no problem making it through the night either thanks to the biggest battery this side of the midrange. Add to that some nice-to-haves that are increasingly harder to find in the high-end segment like a headphone jack, a status LED, and a dedicated microSD slot, and we can see how the Zenfone 6 makes a really compelling case for itself.