I tried both, and for the coffee I use regularly (which isn't as good as it could be, it's not high grade, and it's not fresh ground - it's also less than half the price of "proper" beans) -- I can't really tell the difference.

For really good coffee I haven't tested back-to-back, but I generally find that letting it steep "right way up" is fine. Also letting the coffee steep in a pre-heated cup/kettle/teapot is fine. Maybe this makes a difference if one makes "pretend-espresso" rather than a full cup of "Americano" (actually more like Lungo -- but still not, as the pressure is lower than the initial pressure for a lungo).

I like my aeropress, but it's no espresso machine. It's different from a French press and a pour-over -- but I'm not prepared to claim that it's the best coffee.

This x 1000. To my mind, espousing the inverted method betrays a scant grasp of vacuums and basic physics.

Allowing a drop or two of coffee to escape early to the cup massively outweighs the risks of using very hot water to give something a very high centre of gravity.

Practical point: I've had an Aeropress for years, using it at least once a week, often daily, always inverted.

I've never knocked it over. It's much more stable inverted than you might think.

And ditto from my perspective. But it still bugs me when I have my kids running around that the exception that proves the rule will arise, and it's more robust to have the AP directed into the mug at brew time than inverted, so I just rely on the vacuum to work the magic.*

But for me, the key point is that there's no appreciable difference in the coffee either way.

*Although you might legitimately point out that the whole caboodle is taller as a result doing it the old fashioned way, which increases the chances of it being knocked over.