Singler is becoming a good starter for Pistons so Singler is my first choice. Aminu is the 2nd. He can do everything on the floor, even though he does not in every game but he can contribute to blocks, steals as well as points and rebounds.
Singler is my first choice as well. Especially under these settings. He doesn't really hurt your team in any category.
My next choice is just the hot play of the moment under these league settings, so that would be Morris. Over the past two weeks he's played more valuable ball than Aminu or Gee under your league settings according to basketballmonster rankings.
Aminu is a very very close 3rd choice. Barely choose Morris over him. The better long-term (i.e. more secure) choice is probably Aminu. But if Aminu is on your wire today, that leads me to believe you'll have options down the line should Morris not work out.
I wouldn't pick up Gee. He can actually hurt you in a few places. Without running a full Team Analysis on your team (i.e. I'm not sure if you are intentionally punting any categories), Gee appears to be not worth owning.