for what it is worth I have a couple years use on 2 sets of cheap amazon fans and they seem to work fine. 8milelake was the 'brand' but they seem to be gone now. I'd buy from Amazon again based on this experience.
dual 10" is all I could squeeze behind stock AD rad, They cool the 250 fine, but I need to open some flaps in the back of the shroud I made for better low speed cooling on hot days.
A single large fan would have given more fan surface area but would have interfered with water pump on the inline 6.
I have dual 12" in front of LS swap in Sonoma using a 4.3 Blazer rad. Sequential control from ECU, I don't think the 2nd fan has ever turned on. But that swap has only been on the road since last winter, no real hot days yet. No shroud in this instance, fans just hang from rad using some m3 threaded SS rod and nylocs. (don't waste your time with the zip tie things, they won't stay tight)