Armstrong makes a good product and if you've like the performance I would recommend you stay with it.
Here's why,
The wearlayers in LVT can be quite different from manufacturer to manufacturer even when the specifications seem the same. What this can result in if you start to "mix" manufacturers is a lot of small aggravating problems. Slight height differences, sheen variation (shiny vs. dull), and more importantly to a home owner - difference in maintenance recommendations and products can be significant.
In your case I think the old adage that "If it ain't broke, don't fix it" is pretty accurate.
The other more important thing is that to get a product that would perform as well from another manufacturer (Mannington, Shaw, Mohawk, Karndean, Tarkett) you're going to essentially spend the same kind of money. In the marketplace these products are all essentially within pennies of one another to the dealer. If you see something out there cheaper, especially with the supply chain issues our industry is facing, then you can bet that it isn't the same "quality" of product.
Bear in mind that manufacturers also make different qualities of products within their own lines to make sure that they can meet multiple levels of a consumers buying budget. The cheaper products will have less "bells & whistles" and generally a lesser performance as a result. There's also another "rule of thumb" that's very true within the hard surface flooring world: The cheaper the flooring, the more the labor costs. The reason for this is because the floor prep required to make a cheap floor perform and install correctly and not look terrible is much more exacting. In other words, more expensive floors tend to have a greater margin for error.
Here's an example:
A square edged, thinner product will "telegraph" or show more subfloor imperfections than a bevel-edged or micro-bevel edged product. This is because any unevenness in the subfloor will show as "ledging" (one edge higher than the other) where the pieces come together at the joint. As a result the installer has to make certain that the floor is extremely flat to avoid any ledging. It costs more money to machine the edges during manufacturing as it's a separate process that's performed after the product is made.
Also, be prepared to wait. Right now our industry is experiencing severe supply chain issues and many products are on back order. I've seen everything from a few weeks (2-3) to "probably sometime in January" on lead times.
Wish you the best with your project and let us know how things work out.