In short: AT&T has begun selling two new smartphones on its website (and in its stores). These include the Samsung Galaxy A6, and the LG Stylo 4 Plus. The Galaxy A6 was actually announced a few weeks ago by Samsung and went on sale, unlocked not long after. The Galaxy A6 is on sale from Samsung for $359, but AT&T is selling it for a bit more cash, at $419. It can also be picked up on AT&T NEXT for $14 per month. There's no differences here other than the AT&T model being locked to AT&T (unless you buy it outright and have it unlocked), so you are likely better off buying directly from Samsung.
The LG Stylo 4 Plus on the other hand, is very similar to the Stylo 4 that LG released not too long ago. The Stylo 4 Plus actually sports a bit more RAM at 3GB versus the 2GB on the Stylo 4. Otherwise it is sporting the same 6.2-inch, 2160x1080 resolution display, with the Qualcomm Snapdragon 450 chipset and 32GB of storage. LG does also have a micro SD card slot here for expanding storage, and there is a 3300mAh capacity battery inside.
Background: Both of these smartphones are indeed mid-range devices, though they are not as cheap as other mid-rangers out there, and that is because these share the design language from the higher-end smartphones from each brand. These are being added to AT&T's lineup so that customers can grab something that isn't as expensive as a LG G7 ThinQ or a Samsung Galaxy Note 9.
Impact: As mentioned, the Galaxy A6 is available now for $419 or for $14 per month for 30 months on AT&T NEXT. Now the LG Stylo 4 Plus is priced a bit cheaper at $359 outright, or $12 per month for 30 months. The LG Stylo 4 Plus might be the better option here, since it is priced similar to what LG is selling it for, unlocked, and you get a bit more RAM. Either way, you can buy both of these through the links below.