for normal use as u said those apps, it wont lag.
i never use netflix before, so cant comment on that, but it got the right DRM for the netflix and i read on review , you can watch netflix HD on it.

astro go - cant find on google play store but u can sideload it, working perfect for me
the rest like unifiTV, iflix also working fine.

i never use other china boxes before and im using minix u8-h since 2014, until i upgrade to u9-h last few months.
use it with minix A2 Lite air mouse, its the best experience u can get.

for me, its the best box with firmware support although it quite slow on release, mybe due to few staff@developer working on it.

custom rom also got, last week i flashed it with Android TV os based, but got some minor bugs, well cant blame since its custom rom.

the only cons about minix is the price, mybe due to they hv lots of licence on it, those DRMs, widevine, dolby digital etc
if u want cheaper, mybe can go with mi box