can't decide between TP-Link TL-WN722N and TP-Link TL-WN822N... would anyone know already? I only want a decent one for range, cause the router's downstairs and was wondering if the 2nd one was a bit overkill?

You can never go overkill when it comes to WiFi.

Especially if the card supports external antennas (plugin ones) that could offer a db boost, or allow you to put a directional antenna on there to aim straight at the router for MAX POWAH (those wind surfer things actually kind of do work)

Has this technology gotten better?

Nothing wrong with the technology. Some manufacturers simply don't know how to design reliable networking hardware or have their priorities wrong. Netgear is a prime example. They pushed out lots of fancy-looking devices that deviated significantly from the chipset manufacturer's reference design, and surprise surprise weren't tested properly and performed poorly.

Especially if the card supports external antennas (plugin ones) that could offer a db boost, or allow you to put a directional antenna on there to aim straight at the router for MAX POWAH (those wind surfer things actually kind of do work)

On wireless-N I'd probably go for lower-gain antennas without a reflector, to allow the signal to scatter/reflect off walls as much as possible. More scatter = better diversity and generally better performance.