AK-48 is one of the four strains I keep around, currently. (NYC Diesel, AK-48, Hindu Kush, Papaya.) Occasionally I try a new strain, and if it's better than one of the four I already have, I replace one. AK-48's been with me from the start; never been tempted to phase it out. I'm not currently flowering any, but I have a few AK-48 clones vegging for later crops.
I haven't tried the Papaya yet, but the other three I have. I'd rate those three like this:
Potency: Diesel > AK-48 > Hindu Kush
Yield: Hindu Kush > Diesel > AK-48
Hindu Kush and AK-48 are very close in potency though, and Hindu Kush is a much better yielder, so I tend to grow a lot of the Kush. But the AK-48 is too good for me to give it up, even if it's not a big producer. (It's not a BAD producer or anything, so don't fret.)