Did you notice the date on that article? 7 years is a long time,
but yes, most flash is crap. You can find out much more, and more relevant at Armbian
And now there is class a1 and soon a2. It’s hard to beat samsung evo or evo+ .
An iozone line from my history, if you want true and accurate numbers
iozone -e -I -a -s 100M -r 4k -r 16k -r 512k -r 1024k -r 16384k -i 0 -i 1 -i 2
–edit–
the speed (for SD) is pretty irrelevant if the socket is running at 50 mHz, not switched to 1v8
(as 95% are)