I would say that A is the best out of all of them then B then C then D. A makes it very easy to kill the unit as you would presumably be protecting it. B will kill the unit but not immediately and gives an opportunity for it to take some other unit out unless you have a huge tempo advantage. C gives a small tempo advantage but it could be very hard to use. D might actually be worse than just a swap with a unit due to allowing double threats but could see some tricky uses by compelling your own pieces. So to summarize A>B>C>D. I would value A at 13 B at 12 C at 8 D at 7 they would all be much lower if they didn't have range 3 attack.