mollie13eth added a post in a topic
I think A, B, and C all will shoot at E and E would be dead the first round based on 1/5 + 2/5 + 3/5 = 6/5 = a darn good probability that E is dead
Then D would shoot C, and with his 4/5 probability and there only being 4 people, C would probably be dead in the first round as well.
Next A & B would shoot at D and 1/5 + 2/5 = 3/5 good chance that D is dead
C wouldn't shoot anyone because he's probably dead.
A & B would continue shooting D until D is dead.
Overall best position:
B, because B and A are the last two standing, and B has a better chance of killing A.